Studied by 7 people
State the three parts of the cell theory.
A2.2.1: Cells as the basic structural unit of all living organisms
All organisms are composed of one or more cells.
The cell is the basic unit of life.
All cells come from preexisting cells.
List the functions of life.
A2.2.1: Cells as the basic structural unit of all living organisms
Functions of life: things that all organisms must do to stay alive.
Nutrition: Obtains food for energy & materials in order to grow
Metabolism: Carries out chemical reactions inside the cell
Growth: Increases in size, irreversible (cannot grow smaller)
Response: Can react to changes in the environment
Excretion: Release waste products that can’t be used (toxic or harmful)
Homeostasis: Can keep the conditions inside the organism within a tolerable range
Reproduction: Produce offspring (sexually or aesexually)
Compare the use of the word theory in daily language and scientific language.
A2.2.1: Cells as the basic structural unit of all living organisms
In daily use, a theory is a guess, so there is doubt.
In scientific use, a theory has been shown to be true through repeated observations & experiments. There is no current doubt because there is no evidence that does not support the idea thus far.
Distinguish inductive from deductive reasoning.
A2.2.1: Cells as the basic structural unit of all living organisms
Inductive reasoning uses specific observations to form a general conclusion.
Deductive reasoning uses a general premise to form a specific conclusion.
Outline the process of inductive reasoning that led to the development of the cell theory.
A2.2.1: Cells as the basic structural unit of all living organisms
Biologists examined tissues from both plants & animals and saw that every specimen contained at least one or more cells, allowing them to reason that all living things are composed of one or more cells.
Subcellular components have never been seen to perform the functions of life, while full cells have, suggesting that the cell is the basic unit of life.
We have observed cells coming from other cells, but never spontaneous generation, so all cells must come from preexisting cells.
Outline how deductive reasoning can be used to predict characteristics of a newly discovered organism.
A2.2.1: Cells as the basic structural unit of all living organisms
A deduction will only hold true if the premises are correct. If the premises are incorrect, the deductions will also be incorrect (even if the logical reasoning is valid)
Deductive reasoning can use an existing theory to propose a hypothesis about the characteristics of a newly discovered organism. For instance, if we know all organisms are made of one or more cells and slime molds are living organisms, then slime molds must be made of cells.
Given the magnification of the ocular and objective lenses, calculate the total microscope magnification.
A2.2.2: Microscopy Skills
Total magnification = ocular magnification x objective lens.
Demonstrate how to focus the microscope on a sample.
A2.2.2: Microscopy Skills
Turn the coarse focus knob so that the stage moves upward toward the objectives and move it as close as possible without touching the slide.
Turn the coarse adjustment so that the stage moves down until the image comes into broad focus.
Turn the fine adjustment knob as necessary.
Demonstrate how to make a temporary wet mount and stain a microscopic sample.
A2.2.2: Microscopy Skills
A wet mount is a drop of water used to suspend the specimen between the slide and cover slip.
Procedure for making a wet mount:
Place a sample on the slide
Place a drop of water on the specimen using a pipette
Place the edge of the cover slip over the sample at an angle & lower into place
This prevents air bubbles from being trapped under the cover slip
Take a piece of paper towel & hold it close to one edge of the cover slip (to draw out some water)
A stain is a chemical that binds to structures within the sample to make them look more clear. They are added when making a wet mount slide.
Demonstrate how to draw cell structures seen with a microscope using sharp, carefully joined lines and straight edge lines for labels.
A2.2.2: Microscopy Skills
Drawing materials: drawn with a sharp pencil line on white, unlined paper.
Positioning: It should be centered on the page to add room for labels
Size: It should be a large, clear drawing that occupies at least half a page
Labels: labels should be drawn with straight, horizontal lines with a ruler; labels should form a vertical list & labels should be printed
Technique: Lines should be clear and not smudged, no shading or coloring
Scale: Include a labeled scale bar indicating the estimated size of the sample with the correct number of digits & units
Accuracy: drawn only what is asked for
Title: state what has been drawn and what lens power it was drawn under, informative & centered text (larger than others), including the scientific name italicized or underlined
Measure the field of view diameter of a microscope under low power.
A2.2.2: Microscopy Skills
The field of view (FOV) is the diameter of the area visible through the microscope.
Method 1: Use a ruler to measure the diameter.
Method 2: Diameter (HP FOV) = (Diameter LP x magnification of LP objective)/magnification of HP objective
Calculate the field of view diameter of a microscope under medium or high power.
A2.2.2: Microscopy Skills
The diameter of the field of view under high power often cannot be measured directly, so it must be calculated through an equation:
Diameter (HP FOV) = (Diameter LP x magnification of LP objective)/magnification of HP objective
Use a formula to calculate the magnification of a micrograph or drawing.
A2.2.2: Microscopy Skills
A micrograph is a photo taken down a microscope. The magnification shows how much larger an object appears compared to its real size.
Magnification = (size of the image) ÷ (actual size of the specimen)
If given the magnification of a micrograph or drawing, use a formula to calculate the actual size of a specimen.
A2.2.2: Microscopy Skills
Calculating Specimen Size using Magnification:
Measure a specimen across the widest part of the specimen (using a ruler)
Measure the length of the scale bar in mm
Calculate how many scale bar lengths make up the specimen (Divide length of specimen by length of scale bar)
Multiply the scale bar label by the answer found in step 3
Compare quantitative and qualitative observations.
A2.2.2: Microscopy Skills
Quantitative data is anything that can be counted or measured; numerical data.
Qualitative data is descriptive, referring to things that can be observed but not measured—such as colors.
Define micrograph, electron micrograph, and scale bar.
A2.2.2: Microscopy Skills
Micrograph: a photo taken down a microscope
Electron micrograph: a photo taken with electron microscopes
Scale bar: a horizontal line drawn on the image to show how long the line is in the real specimen.
Calculate the actual size and magnification of a specimen in a micrograph or drawing.
A2.2.2: Microscopy Skills
Calculating magnification:
Measure the scale bar on the photograph in mm with your ruler
Convert these mm into the same units as the scale bar
Divide the image scale bar length (Image size) by the actual scale bar length (actual size) to find magnification
Calculating actual size:
Measure a specimen across the widest part of the specimen (using a ruler)
Measure the length of the scale bar in mm
Calculate how many scale bar lengths make up the specimen (Divide length of specimen by length of scale bar)
Multiply the scale bar label by the answer found in step 3
Define eyepiece graticule and stage micrometer.
A2.2.2: Microscopy Skills
An eyepiece graticule is a scale inside the eyepiece used to measure the actual size of a structure when using a microscope.
A stage micrometer is a glass slide with a precise scale etched on it.
Measure sizes using an eyepiece graticule and micrometer.
A2.2.2: Microscopy Skills
Find out how many eyepiece divisions your specimen is. Record the number
Remove the slide. Place the stage micrometer on microscope stage – DO NOT CHANGE OBJECTIVE
Rotate the graticule until it’s parallel to the micrometer scale
Adjust the alignment of the scales so that the 0 values are lined up (or whole number lined up to whole number).
Find the ratio between eyepiece divisions and micrometers divisions
Calculate the distance of one eyepiece
Multiply the total number of specimen divisions in specimen by the number calculated in step 6
Define resolution and magnification.
A2.2.3: Developments in microscopy
Resolution: Making the separate parts of an object distinguishable by eye; the degree of detail visible in an image created by the instrument
Magnification: How much larger an object appears compared to its real size
Compare the functionality of light and electron microscopes.
A2.2.3: Developments in microscopy
Light microscopes can observe living or dead specimens in color, but can only magnify up to 2000x. Electron microscopes can only observe dead things in a fixed plastic material and only in black and white images, but it can magnify up to 1 million times.
Light microscopes can have more flexibility in use, but electron microscopes can magnify something even more.
Light Microscopes | Electron Microscopes |
Simple & easy specimen preparation | Complex & lengthy specimen preparation |
Magnifies up to 2000x | Magnifies up to 1,000,000x |
Specimens may be living or dead | Specimens are dead & must be fixed in a plastic material |
Produces images in color | Only gives black and white images |
State a benefit of using fluorescent stains to visualize cell structures.
A2.2.3: Developments in microscopy
Fluorescent stains bind to specific chemicals, but not others, which can generate particularly bright images.
Outline the process of visualizing specific proteins in cells using immunofluorescence technology.
A2.2.3: Developments in microscopy
In immunofluorescenc technology, fluorescently-stained antibodies bind to specific target proteins within a cell.
The protein tagged with immunofluorescence can be located and tracked as it moves in the cell.
Outline the process of producing images of cell surfaces using freeze-fracture electron microscopy.
A2.2.3: Developments in microscopy
In freeze-fracture electron microscopy, cells are rapidly frozen. Then, they are fractured along lines of weakness. The surfaces are etched with a coating, which can be viewed using an electron microscope.
Outline the process of visualizing specific proteins using cryogenic electron microscopy.
A2.2.3: Developments in microscopy
A solution with the protein is frozen then bombarded with a beam of electrons. Afterward, a computer analyzes patterns of diffraction off the sample to produce an image of the structure.
Outline the function of structures that are common to all cells.
A2.2.4: Structures common to cells in all living organisms
The plasma membrane separates the interior of the cell from its surroundings and controls what materials are let into the cell.
The cytoplasm is mostly made of water, so many solutes (including salts, fatty acids, sugars, amino acids, and proteins) are dissolved, which allows metabolism to occur.
DNA is used as the genetic material by all living organisms.
Ribosomes catalyze the synthesis of polypeptides during translation (protein synthesis).
Outline the functions of the following structures of an example prokaryotic cell: cell wall, plasma membrane, cytoplasm, 70s ribosome, and nucleoid DNA.
A2.2.5: Prokaryotic cell structure
The cell wall provides shape and strength, and it allows the cell to withstand turgor pressure without bursting.
The plasma membrane regulates what materials move into and out of the cell, and separates the internal components of the cell from outside environment.
The cytoplasm is a gel-like fluid substance (mostly water with many dissolved molecules) that is the site of metabolic reactions.
The 70s ribosome builds proteins during translation.
Nucleoid DNA is the main DNA of the cell. It is not enclosed in membrane, so it is found freely in the cytoplasm. It is a single loop and not wrapped around proteins (“naked”).
Define the term “naked” in relation to prokaryotic DNA.
A2.2.5: Prokaryotic cell structure
“Naked” means that DNA is not associated with (wrapped around) proteins. DNA in nucleoids and plasmids are naked in prokaryotic cells.
Compare and contrast prokaryotic and eukaryotic cell structure.
A2.2.6: Eukaryotic cell structure
Both prokaryotic cells (archaea and bacteria) and eukaryotic cells (fungi, plant, animal) have ribosomes, DNA, a cell membrane, and a cytoplasm.
Eukaryotes have many more membrane-bound structures with specialized functions including:
Nucleus
Free and bound 80s ribosomes
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Golgi apparatus
Vesicles
Lysosome
Mitochondria
Chloroplast
Vacuole
Microtubules & Centrioles
Cytoskeleton
Cilia & Flagella
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Label a diagram of a eukaryotic cell.
A2.2.6: Eukaryotic cell structure
Outline the function of the following structures in the eukaryotic cell: plasma membrane, cytoplasm, 80s ribosomes, nucleus, mitochondria, chloroplast, endoplasmic reticulum, Golgi apparatus, vesicles, vacuoles, lysosomes, cytoskeleton of microtubules and microfilaments.
A2.2.6: Eukaryotic cell structure
The plasma membrane regulates what materials move into and out of the cell, and separates the internal components of the cell from outside environment.
The cytoplasm is a gel-like fluid substance (mostly water with many dissolved molecules) that is the site of metabolic reactions.
The 80s ribosomes catalyze the synthesis of polypeptides during translation (protein synthesis). They can be “free” (floating in the cytoplasm, synthesizing polypeptides used within the cell) or “bound” (attached to the RER, synthesizing polypeptides secreted from the cell, or become integral proteins in cell membrane)
The nucleus contains DNA (in chromosomes) to store information for making proteins via transcription & translation. It has the nucleolus, where ribosome subunits are made.
The rough endoplasmic reticulum (RER), a series of connected flattened membranous sacs, has bound ribosomes that synthesize polypeptides and release it to the inside of the RER.
The smooth endoplasmic reticulum (SER), a series of connected flattened mambranous sacs continous with the RER, synthesizes phospholipids and cholesterol for the formation and repair of membranes. It lacks ribosomes and is not involved with protein synthesis.
The golgi apparatus modifies polypeptides into functional states. It sorts, concentrates, and packs proteins into vesicles. Then, the vesicles are dispatched to either lysosomes, plasma membranes, or secreted to the outside of cell.
Vesicles contain and transport materials within the cells (transport or secretory).
Vacuoles store water and maintain turgor pressure (mechanism the plants use to remain upright).
Lysosomes contain enzymes that work in oxygen-poor and lower pH areas. These enzymes digest large molecules to degrade and reculce the components of the cell’s own organelles (if they are old or damaged, or if the cell is “starving” without nutrients). Lysosomes also digest pathogens, allowing for immune defense.
The cytoskeleton of microtubules and microfilaments help maintain the cell’s shape, organizes the cell parts, and enables cells to move and divide.
List the common processes carried out by all life.
A2.2.7: Processes of life in unicellular organisms
Metabolism
Homeostasis
Excretion
Growth
Nutrition
Movement
Reproduction
Response to stimuli
(MR MR HENG)
Define metabolism, homeostasis, excretion, growth, nutrition, movement, reproduction and response to stimuli.
A2.2.7: Processes of life in unicellular organisms
Metabolism: Carry out chemical reactions inside the cell
Viruses don’t do metabolism → not considered self-sustaining life
Homeostasis: Can keep internal environment/conditions within a tolerable range, despite changes in external environment
Water’s high specific heat capacity allows us to maintain homeostasis
Excretion: Excrete metabolic waste matter; Release waste products that can’t be used (toxic or harmful)
Humans: lungs and kidneys
Plants: via leaves, roots, stem
Unicellular organisms: through cell membrane (so cells must have a large surface area:volume ratio)
Growth: grow and/or develop in the lifespan
Growth; Increases in size & mass, irreversible (cannot grow smaller)
Development: transformation of the organism through its lifespan (like a butterfly)
Nutrition: Obtains energy & matter
Autotrophs: use external energy sources (usually sun) to synthesize carbon compounds from simple inorganic substances
Plants
Heterotrophs: use carbon dioxide compounds obtained from other organisms to synthesize carbon compounds required
Animals
Movement: adaptations for movement
Sessile organisms: stay in one place
Motile organisms: mobile
Reproduction: Produce offspring (sexually or asexually)
Sexual reproduction: 2 parents, fusion of haploid sex cells from each parent
Meiosis → genetically unique offspring, increases genetic variation
Asexual reproduction: only one parent
Binary fission or mitosis → All genetically identical offspring
Response to stimuli: Can recognize & respond to changes in environmental conditions
react to changes in the environment
Describe characteristics of Paramecium that enable it to perform the functions of life.
A2.2.7: Processes of life in unicellular organisms
Paramecium: eukaryotic organisms, live in freshwater environments, carries out all functions of life
Metabolism: cytoplasm contains dissolved enzymes that catalyze metabolic reactions (like digestion, synthesis of cellular structures)
Reproduction: the nucleus of the cell divides by mitosis to make another nuclei before the cell reproduces asexually; 2 paramecium can fuse before dividing (to carry out a form of sexual reproduction)
Movement: beats cilia to move in different directions in its environment
Response: can move (through cilia) to respond to changes in the environment
Homeostasis: excess water is collected in a pair of “contractile vesicles” that swell & expel water through an opening in the cell membrane
Excretion: waste products from digestion are excreted through an anal pore
Nutrition: eats smaller unicellular organisms
Growth: cell wall grows until it reaches a maximum surface level to volume ratio (then it divides)
Describe characteristics of Chlamydomonas that enable it to perform the functions of life.
A2.2.7: Processes of life in unicellular organisms
Chlamydomonas: eukaryotic organisms; lives in soil, fresh water, oceans, snow on mountaintops; carries out all functions of life
Metabolism: cytoplasm & chloroplast contain dissolved enzymes to catalyze metabolic reactions (digestion, photosynthesis, cellular respiration, synthesis of cellular structures)
Reproduction: the nucleus divides through mitosis to make another nuclei asexual reproduction; nuclei can also fuse & divide to carry out a form of sexual production
Movement: has 2 flagella to help it move
Response: has a sensitive “eyespot” to sense light, uses flagella to move to the light
Homeostasis: excess water is collected in a pair of “contractile vesicles” that swell & expel water through an opening in the cell membrane
Excretion: oxygen (byproduct of photosynthesis, waste product) diffuses out through cell membrane
Nutrition: uses photosynthesis for nutrition (chlamydomonas is an autotroph)
Growth: cell grows until it reaches a maximum surface level to volume ratio (then it divides)
Compare and contrast the structures of plant, animal and fungal cells with reference to cell walls, vacuoles, chloroplasts, centrioles, cilia and flagella.
A2.2.8: Differences in eukaryotic cell structure between animals, fungi and plants
Plant cells have a cell wall made of cellulose, while Fungal cells have a cell wall made of chitin. Animal cells don’t have a cell wall.
Plant cells have large, permanent vacuoles that take up most of the cell and are responsible for nutrient, waste, and water storage, as well as maintaining turgor pressure. Fungal cells can have large or small vacuoles depending on the species. Animal cells have small, temporary vacuoles that store materials and waste products.
Only plant cells have chloroplasts (and other plastids such as chromoplasts and amyloplasts).
Plant cells and fungi do not have centrioles, while animal cells have centrioles for cell division (mitosis and meiosis).
Plant and fungal cells do not have cilia and flagella, but some animal cells do.
Describe features of skeletal muscle fibers that make them an atypical cell.
A2.2.9: Atypical cell structures in eukaryotes
Skeletal muscle fiber results from the fusion of multiple cells. Thus, there is a single large eukaryotic cell that has multiple nuclei (more than one nucleus).
Describe features of aseptate fungal hyphae that make them an atypical cell.
A2.2.9: Atypical cell structures in eukaryotes
Fungal cells typically have hyphae, which are tubular projections of multicellular fungi that form an underground filamentous network (mycelium), that are separated.
However, fungal hyphae are sometimes not divided not into individual cells (called aseptate hyphae). This forms a continuous cytoplasm along the length of the hyphae.
Aseptate hyphae are not made of clearly defined individual cells, instead they are continuous structures with multiple nuclei.
Describe features of red blood cells that make them an atypical cell.
A2.2.9: Atypical cell structures in eukaryotes
Red blood cells transport oxygen in vertebrates.
During their mutation, red blood cells discard their nucleus and mitochondria. This causes the cells to become very small, increasing their surface area to volume ratio, a characteristic that makes them more efficient in gas exchange and enhances their ability to move through narrow capillary vessels.
Therefore, red blood cells don’t have a nucleus or mitochondria!
Describe features of phloem sieve tube elements that make them an atypical cell.
A2.2.9: Atypical cell structures in eukaryotes
Phloem sieve tube elements are specialized cells that are part of the phloem (the tissue that transports organic compounds made during photosynthesis throughout a plant).
During their development, phloem sieve tube elements lose their nucleus and other organelles, which provides more space for the transport of phloem sap.
Thus, the phloem sieve tube elements don’t have a nucleus & other organelles!
Compare the number of nuclei in aseptate fungal hyphae, skeletal muscle, red blood cells and phloem sieve tube elements.
A2.2.9: Atypical cell structures in eukaryotes
Both aseptate fungal hyphae and skeletal muscle have many nuclei in one large cell.
On the other hand, both red blood cells and phloem sieve tube elements have no nuclei.
Recognize features and identify structures in micrographs of prokaryotic cells (inclusive of the plasma membrane, nucleoid region, ribosomes and cell wall).
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Plasma membrane: pushed against the cell wall
Controls the flow of substances in and out of the cell
Nucleoid region: light-colored, irregularly-shaped
Contains the single, looped chromosome of DNA
Ribosomes: little black dots
Responsible for protein synthesis
Cell Wall: a dark line around the outside of the cell
Provides strength and structure
Flagellum are longer than Pili.
Recognize features and identify structures in micrographs of eukaryotic cells (inclusive of the plasma membrane, nucleus, mitochondrion, chloroplast, vacuole, rough and smooth endoplasmic reticulum, Golgi apparatus, secretory vesicle, ribosomes, cell wall, cilia, flagella and microvilli).
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Plasma membrane: a membrane either against a cell wall (plant or fungi) or alone (animal)
Controls the flow of substances in and out of the cell
Nucleus: Double membrane, large sphere-ish shape, pores may be visible
Usually surrounded by endoplasmic reticulum
Animal cells: in the center
Plant cells: pushed up against the wall
Stains darker (DNA & chromosomes stain dark)
May have lighter regions internally
Where the DNA is replicated and transcribed
Mitochondrion: Circular or ovoid shape, have infoldings of membrane called cristae, bound by a double membrane
Tends to stain darker
Produces ATP by aerobic cell respiration
Chloroplast: Internal stacks of thylakoid membrane, bound by a double membrane
Adapted for photosynthesis
Captures light energy & uses it with water and carbon dioxide to produce glucose
Vacuole: Clear due to fluid inside
Bound by a single membrane called tonoplast
Plant cell vacuoles fill much of cell volume & pushes organelles to side of cell
Stores water and/or metabolic waste
Vacuole maintains turgor pressure in plant cells
Rough endoplasmic reticulum: Series of connected, flattened membranous sacs, lined with dots (ribosomes)
Usually found near the nucleus
Synthesizes & transports proteins
Has bound ribosomes to synthesize the polypeptide & release it to the inside of RER
Smooth endoplasmic reticulum: Series of connected, flattened membranous sacs
No dots (no ribosomes)
Recognize features and identify the plasma membrane in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
a membrane either against a cell wall (plant or fungi) or alone (animal)
Features:
Made of phospholipids
Controls flow of substances in and out of the cell
Recognize features and identify the nucleus in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Large sphere-ish shape
Usually surrounded by endoplasmic reticulum
Animal cells: in the center
Plant cells: pushed up against the wall
Stains darker (DNA & chromosomes stain dark)
May have lighter regions internally
Features:
Double membrane
Pores may be visible
Where DNA is replicated & transcribed
Recognize features and identify the mitochondrion in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Circular or ovoid shape
Have infoldings of membrane called cristae
Tend to stain darker
Features:
Bound by a double membrane
Produces ATP by aerobic cellular respiration
Recognize features and identify the chloroplast in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Internal stacks of thylakoid membrane
Features:
Bound by a double membrane
Found only in plant cells
Adapted for photosynthesis
Captures light energy & uses it with water and carbon dioxide to produce glucose
Recognize features and identify the vacuole in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Clear due to fluid inside
Plant cell vacuoles fill much of cell volume & pushes organelles to side of cell
Features:
Bound by a single membrane called tonoplast
Stores water and/or metabolic waste
Vacuole maintains turgor pressure in plant cells
Recognize features and identify the rough endoplasmic reticulum in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Series of connected, flattened membranous sacs
Lined with dots (ribosomes)
Usually found near the nucleus
Features:
Has ribosomes
Synthesizes & transports proteins
Has bound ribosomes to synthesize the polypeptide & release it to the inside of RER
Recognize features and identify the smooth endoplasmic reticulum in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Series of connected, flattened membranous sacs
No dots (no ribosomes)
Usually found further from the nucleus than the rough ER
Features:
Doesn’t have ribosomes
Synthesizes phospholipids & cholesterol for the formation & repair of membranes
Recognize features and identify the golgi apparatus in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Flattened stacks
Inside of the stack is clear
Curved
Vesicles around the Golgi Apparatus
Features:
Modifies polypeptides into functional state
Sorts, concentrates, and packs proteins into vesicles
Recognize features and identify the secretory vesicles in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Tends to be circular
May be clumped towards one side in secretory cells
Often stain dark due to proteins being stored & transported
Features:
Membrane-bound
Contain & transport materials within cells
Recognize features and identify the ribosomes in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Look like tiny dots
Found throughout the cytoplasm
Often the smallest structure visible in electron micrograph
Features:
Synthesizes polypeptides during translation (which will become proteins that function within the cell)
Recognize features and identify the cell wall in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
A thicker line around the outside of the cell
Tends to be a light gray color
Features:
External to the cell membrane
In fungi & plant cells
Helps develop turgor pressure & protects the cell
Recognize features and identify the cilia in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Many extensions projecting from cell membrane
Features:
Contain microtubules arranged in a “9+2” pattern (9 pairs of microtubules on the outside and 2 pairs of microtubules in the middle)
Regular movement of cilia → cell moving through a solution (typical for many single-celled organisms)
Moving water & its contents across the surface of the cell
Recognize features and identify the flagella in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Long protrusion from cell membrane
Usually only a few (1-2) are present
Features:
Contain microtubules arranged in a “9+2” pattern (9 pairs of microtubules on the outside and 2 pairs of microtubules in the middle)
Used to move a cell through a solution
Recognize features and identify the microvilli in micrographs of eukaryotic cells.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Identification:
Many short extensions of the cell membrane
Usually shorter & more tightly packed than cili
Features:
Doesn’t have a 9+2 arrangement of microtubules
Protrusions of the cell membrane
Increase the surface area for absorption
Identify cells in light and electron micrographs as prokaryote, plant, or animal.
A2.2.10: Cell types and cell structures viewed in light and electron micrographs
Prokaryotic cells do not have a nucleus, only a nucleoid region, and no membrane-bound organelles.
Plant cells have clearly-visible nuclei with a fixed shape and a clear cell wall (light microscope). In an electron microscope, plant cells have large vacuoles that take up most of the space.
Animal cells have clearly-visible nuclei with a fixed irregular shape (no cell wall).
Draw and annotate diagrams of the nucleus as shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
Double membrane
Clear pores
Annotations:
Nucleus contains chromosomes
Chromosomes contain genetic information for cell growth & development
Produces RNA required for translation
Draw and annotate diagrams of mitochondrion as shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
Draw a smooth outer membrane
Highly folded inner membrane
Annotations:
Produces ATP by aerobic respiration
Draw and annotate diagrams of chloroplasts as shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
Surrounded by a double membrane
A series of interconnected membranes within the chloroplast
Annotations:
Contain chlorophyll
Carry out photosynthesis for the plant
Draw and annotate diagrams of sap vacuoles shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
A single membrane
Takes up most of the space in the center of plane cells
Annotations:
Found in plant cells
Stores nutrients and wastes, maintains turgor pressure
Turgor pressure: the force within the cell that pushes the plasma membrane against the cell wall
Draw and annotate diagrams of Golgi appartus shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
A series of curved membranes
Vesicles located around the ends of the membranes
Annotations:
Receives proteins from the rough endoplasmic reticulum
Modifies proteins & packages them in vesicles for secretion
Draw and annotate diagrams of rough endoplasmic reticulum shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
A series of tubules with clear dots representing ribosomes
Usually located near the nucleus
Annotations:
The site of protein synthesis
Proteins then transported to Golgi apparatus
Draw and annotate diagrams of smooth endoplasmic reticulum shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
A series of tubules without any ribosomes attached
Usually located near the plasma membrane, away from the nucleus
Annotations:
Production of lipids
Detoxification of harmful substances
Draw and annotate diagrams of chromosomes shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
Visible during mitosis and meiosis
Initially appear as 2 chromatids (prophase) but later separate into individual chromosomes (anaphase)
Annotations:
Located in the nucleus
DNA wrapped around histone proteins
Contain genetic information for cell growth & development
Draw and annotate diagrams of a cell wall shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
A thick, dark line around the boundary of the cell
Annotations:
Provides strength and structure to plant cells
Maintains turgor pressure (prevents cell from bursting)
Draw and annotate diagrams of the plasma membrane shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
Animal cells: The outer boundary, represent by a thin line
Plant cells: Pushed against the thick cell wall, Can be labelled as the innermost part of the cell wall
Annotations:
Controls what enters & exits the cell
Draw and annotate diagrams of secretory vesicles shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
Small enclosed membranes
Represent with small circles, with at least one fusing with the plasma membrane
Annotations:
Transport proteins from the Golgi apparatus to the plasma membrane (where they’re secreted by exocytosis)
Draw and annotate diagrams of microvilli shown in electron micrographs. Include the functions in annotations.
A2.2.11: Drawing and annotation based on electron micrographs
Drawing:
finger-like projections from the cell
Present on one surface of the cell
Annotations:
Increase the surface area of the cell
Increases available surface area for transport of materials
Explain the origin of mitochondria with reference to endosymbiosis
A2.2.12: Origin of eukaryotic cells by endosymbiosis
Mitochondria have have been an aerobic bacteria that used oxygen in aerobic cellular respiration. A larger, host cell ingested aerobic cells. Its fluid membrane allowed the bacteria to enter, with an outer membrane developing as it entered the bacteria. However, some bacterial cells may have remained alive and continued to perform respiration within the host cell (instead of being digested). This developed a close, mutually beneficial relationship between the bacteria and host cell (symbiosis). They may have become so dependent on each other that they became one cell. The bacteria cell went through a series of changes (specialized) so that the larger cell could have ATP, and the bacteria cell developed into a mitochondria.
Explain the origin of chloroplast with reference to endosymbiosis.
A2.2.12: Origin of eukaryotic cells by endosymbiosis
Chloroplasts may have originally been photosynthetic bacteria. A larger cell may have ingested these bacteria. Its fluid membrane allowed the bacteria to enter, with an outer membrane developing as it entered the bacteria. but some bacterial cells have remained alive, instead of being digested. The bacteria continued to perform photosynthesis within the host cell. This developed a close, mutually beneficial relationship between the bacteria and host cell (symbiosis). They may have become so dependent on each other that they became one cell.
Describe the genetic, structural and behavioral evidence for the endosymbiotic theory.
A2.2.12: Origin of eukaryotic cells by endosymbiosis
The endosymbiotic theory explains how a cell could progress from a simple, non-compartmentalized prokaryote into a complex, highly-compartmentalized eukaryote
Genetic evidence:
Mitochondria and chloroplasts both have circular naked DNA like that of prokaryotic cells
But eukaryotic cells have linear DNA wrapped around histone proteins
Mitochondria and chloroplasts share common DNA sequences with prokaryotes
Structural evidence:
Mitochondria and chloroplasts are the same approximate size and shape as prokaryotes.
Mitochondria and chloroplasts have a double membrane
Their own cell membranes (inner membrane) + the cell membrane from when it was engulfed by the host cell (outer membrane)
Mitochondria and chloroplasts both have their own 70s ribosomes
Functional evidence:
Mitochondria and chloroplasts move independently within the eukaryotic cell
Mitochondria and chloroplasts produce their own proteins with their own 70s ribosomes
Mitochondria and chloroplasts reproduce independently of the host cell (through a process similar to binary fission)
Mitochondria and chloroplasts are inhibited by antibiotics, like prokaryotes are
Outline the benefits of cell specialization in a multicellular organism.
A2.2.13: Cell differentiation as the process for developing specialized tissues in multicellular organisms.
Cell specialization in a multicellular organisms allow cells to be less susceptible to predation. It also makes DNA less likely to be damaged by natural or environmental mutagens. Genes are also protected from damage from mutagens because fewer genes are expressed.
Define differentiation.
A2.2.13: Cell differentiation as the process for developing specialized tissues in multicellular organisms.
Differentiation is the development of specialized structures and functions in cells.
Describe the relationship between cell differentiation and gene expression.
A2.2.13: Cell differentiation as the process for developing specialized tissues in multicellular organisms.
Cell differentiation occurs when cell types express different genes.
Proteins bind to specific base sequences in DNA to regulate differentiation in gene expression.
Different tissues are made from cells that have differentiated (because they express different genes) to have different structures and functions.
State that multicellularity has evolved repeatedly.
A2.2.14: Evolution of multicellularity
Multicellularity has evolved repeatedly.
It has evolved independently many times in eukaryotes.
List groups of organisms that are multicellular.
A2.2.14: Evolution of multicellularity
All plants
All animals
Most, but not all, fungi
Many, but not all, algae
Outline the steps in the evolution of multicellularity.
A2.2.14: Evolution of multicellularity
First, single cells clustered together to form cellular clusters. This may have occurred when a group of independent cells came together or when daughter cells failed to separate when a unicellular organism divided (forming an aggregate of identical cells).
After that, cells in the cluster differentiated for specialized functions.
Note 
Flashcard (102)