The Cell (A2.2)

what are the 3 main aspects of the cell theory?

• all living things are composed of cells

• cells are the basic unit of structure and function in living things

• cells come from pre-existing cells

what is deductive reasoning?

progression from a general idea to a specific conclusion

all organisms carry out what processes of life?

Mr. Sheng:

• Metabolism

• Reproduction

• [response to]Stimuli

• Homeostasis

• Excretion

• Nutrition

• Growth

what is homeostasis

the maintenance of internal conditions within a narrow range

what is excretion

the removal of metabolic waste from an organism

What is response to stimuli

• the ability of organisms to respond to internal/external stimuli

• changing the position of the organism

what is metabolism

the sum of all the biochemical reactions that occur in living organisms

what is reproduction

the production of offspring, either sexually of asexually

what is nutrition

the processes that organisms use to obtain and use food (nutrients) for energy, growth, and repair

what is growth

the increase in mass, size, or number of cells of an organism

what are the features shared by all cells?

• phospholipid (plasma membrane)

• cytoplasm

• DNA

• Ribosomes

what are the 2 types of cells

• prokaryotic

• eukaryotic

what does a phospholipid do?

controls what enters and exits the cell

what does the cytoplasm do?

• composed of mainly water

• where most metabolism occurs

what does DNA do?

genetic material

what do ribosomes do?

used for protein synthesis

what is the difference between staphylococcus and bacillus in a prokaryotic cell

Staphylococcus: circular structure

Bacillus: rod structure

what is the structure of a prokaryotic cell? (5)

• cell wall

• plasma membrane

• cytoplasm

• naked DNA in a look (nucleoid)

• 70S ribosomes

what is the function of the cell wall in a prokaryotic cell?

• provides the cell with strength and support

• prevents the cell from bursting

• composed of peptidoglycan

what is the function of the nucleoid in a prokaryotic cell?

• naked DNA twisted in a loop

• no nuclear membrane

• contains a singular circular chromosome with DNA (no protein)

what is the function of the 70S ribosomes in a prokaryotic cell?

• responsible for protein synthesis

what is the structure of a eukaryotic cell? (10)

• plasma membrane

• cytoplasm

• nucleus

• mitochondria

• smooth endoplasmic reticulum (SER)

• rough endoplasmic reticulum (RER)

• 80S ribosomes

• Golgi apparatus

• lysosomes

• cytoskeleton

what is the function of the nucleus in a eukaryotic cell? (3)

• double membrane with pores

• contains DNA (chromosomes)

• has histones bound to it

what is the function of the mitochondria in a eukaryotic cell?

• site of aerobic respiration

  • produces ATP

• has a double membrane

what is the function of the SER in a eukaryotic cell?

• produces lipids

• detoxifies blood

• no ribosomes

what is the function of the RER in a eukaryotic cell?

• site of protein synthesis

• protein is designed to leave the cell

• single membrane

• send proteins to the Golgi apparatus

where are the 80S ribosomes in a eukaryotic cell?

• on the rough ER

what is the function the Golgi apparatus in a eukaryotic cell?

• packages proteins into vesicles for export

• single phospholipid bilayer

what is the function of the lysosomes in a eukaryotic cell?

• special vesicles w/ digestive enzymes

• involved in the digestion of large molecules

what does the cytoskeleton do

• made of microtubules + microfibers

• gives cell structure

• no ribosomes

what are the similarities between prokaryotic and eukaryotic cells? (4)

both have:

• phospholipid membrane

• cytoplasm

• DNA

• ribosomes (70S in p, 80S in e)

what is the difference in membrane bound organelles between prokaryotic and eukaryotic cells?

prok: not present

euk: present

what is the difference in mitochondria between prokaryotic and eukaryotic cells?

prok: not present

euk: present

what is the difference in location of chromosomes between prokaryotic and eukaryotic cells?

prok: Nucleoid region in the cytoplasm

euk: Nucleus

what is the difference in number of chromosomes between prokaryotic and eukaryotic cells?

prok: one

euk: many

what is the difference in shape of chromosomes between prokaryotic and eukaryotic cells?

prok: Loop of DNA

euk: Linear

what is the difference in protein associated with chromosomes between prokaryotic and eukaryotic cells?

prok: NONE

euk: DNA wrapped around histone proteins

what is the difference in ribosomes between prokaryotic and eukaryotic cells?

prok: small 70S

euk: large 80S

what is the difference in cell wall between prokaryotic and eukaryotic cells?

prok: composed of peptidoglycan

euk: plants (cellulose), fungi (chitin), animals (none)

what is the difference in cell size between prokaryotic and eukaryotic cells?

prok: smaller

euk: larger

what are the differences between an animal cell, a fungi cell, and a plant cell?

Feature	Animal	Fungi	Plant
Cell Wall	not present	chitin cell walls	cellulose cell walls
Vacuoles	small; involved in storing materials and waste products	small or large; depends on the species of fungi	1 large vacuole; involved in storing nutrients and waste
Centrioles	present	not present	not present
Plastids (what gives the plant color)	not present	not present	found in: - chloroplasts - chromoplasts - amyloplasts
Cilia and flagella	present in some animal cells	not present	not present

what are some atypical cells and nuclei (4)

• aseptate fungal hyphae

• skeletal muscle cells

• red blood cells

• phloem sieve tube elements

what type of atypical cell is this?

Septate hyphae: has a cell wall

what type of atypical cell is this?

Aseptate hyphae: cell wall removed

what type of atypical cell is this?

skeletal muscle cell

what type of atypical cell is this?

red blood cells

what type of atypical cell is this?

phloem sieve tube + elements

what type of cell is this

prokaryotic:

• there is a clear nucleoid region

• no nucleus present

what type of cell is this

plant cell:

• nuclei are visible

• fixed regular shape

• clear cell wall

what type of cell is this

animal cell:

• nuclei are visible

• don’t have a cell wall around them

where is the nucleoid region?

B: nucleoid region is lighter, irregularly shaped region within the cytoplasm

where is the cell wall

A: seen as a dark line around the outside of the cell

what does the nucleus look like?

the large dark circle with lighter spots what represent pores

what does the mitochondria look like

• has a double membrane

• outer membrane is smooth

• highly folded inner membrane (cristae)

  • represented through lines in a micrograph

what does the chloroplast look like

• has a double outer membrane

• has many membranes within the chloroplast

what does the sap vacuole look like

• large vacuole with a single membrane

• located in the centre of the cell

• pushes all the other organelles against the cell wall

what does the rough endoplasmic reticulum look like

• rough appearance

• has ribosomes (black dots) all over it

what does the smooth endoplasmic reticulum look like

• no ribosomes present

• smooth appearance

what does the Golgi apparatus look like

• a series of stacked, flatten membranes

• small vesicles around it

what does a chromosome look like

• become visible during mitosis and meiosis

• consist of 2 elongated DNA molecules

what do the ribosomes look like

• spherical dots with a dark center

• found floating in the cytoplasm

• found attached to the endoplasmic reticulum

what does the cell wall look like

• a line surrounding the plant cell

what does a plasma membrane look like

• pushed against the inside of the cell (plant cells)

• the outer boundary of the cell (animal cell)

what do the microvilli look like

• appear as long finger-like extensions of a cell

what are the factors that make a scientific theory

• based on evidence

• lots of science to back it up

what is an example of a scientific theory

endosymbiotic theory

what is the endosymbiotic theory

• explains that a sexually reproducing eukaryotic cell with a nucleus engulfed a small aerobic prokaryotic cell

• the 2 cells worked together and developed a mutualistic (symbiotic) relationship with the host cell

• the host cell provides food while the engulfed cell produces ATP energy

• the smaller cell (aerobic cell) then evolves into mitochondria and leaves the host

what is the evidence for the endosymbiotic theory (5)

mitochondria + chloroplasts:

• have a double membrane

• have a single circular chromosome (w/ naked DNA)

• have 70S ribosomes

• reproduce through binary fision

• similar size to modern prokaryotes

what is cell differentiation

some genes are turned on and some are turned off

what triggers different patterns of gene expression?

changes in the internal or external environment

what are the advantages of multicellularity

• tend to be larger

• have longer life spans

• the death of one or a few cells doesn’t kill the organism

• are more complex due to cell specialization

what are the advantages of immunofluorescence (4)

• are specific

  • scientists can study the location, distribution, and quantity of specific biomolecules

• can be used with living tissue

  • allows scientists to study cell division

• can be used to detect molecules at low concentrations

• can be used to label different molecules

what is immunofluorescence used for

to visualize specific protein or antigen in cells by binding a specific antibody to a fluorescent dye

easy way to remember how immunofluorescence works?

navigating around the cells is like navigating around a city (using lights)

what is the formula to calculate the magnification of a cell

I (what you see the image as)/A (actual size)

what is the formula to calculate the actual size of a cell

I (what you see)/M (magnification)

what is the formula to calculate the image of a cell

A (actual size) x M (magnification)

what is 1,000mm in µm

1,000,000µm

(add 3 0s)

what is the order starting from 1 centimeter

1cm, 10mm, 10,000µm, 10,000,000nm

what number is the actual size

0.9μm

Calculate the magnification of the image

1. M = I/A

2. I = 1cm; A = 1µm

3. cm —> µm is 10,000µm

4. 10,000µm/1 = 10,000X

calculate the length of the cell body

1. A = I/M

2. I = 2.5cm; M = 10,000X (from prev. q)

3. 2.5cm/10,000X = 25,0000µm/10,000µm

4. = 25µm

what is freeze fracture electron microscopy

membranes are rapidly frozen then fractured in area of weakness to allow scientists to analyze the structure of plasma membranes and to identify the integral proteins

what is the cryogenic electron microscope

photographs what happens to proteins in real life apart from just their crystalized structure

light vs. electron microscopes (5)

Advantages of a light microscope	Advantages of an electron microscope
easy to use cheap uses light beams low resolution cannot see organelles	very expensive hard to use uses electron beams high resolution can see organelles