Cell Biology

Name the 4 types of macromolecules used to construct a cell

1. Lipids

2. Carbohydrates

3. Nucleic Acids

4. Proteins

What are the levels of organization in a body?

1. Chemical level

2. Cellular level

3. Tissue level

4. Organ level

5. Organ system level

6. Organismal level

Name 5 types of nucleic acids

1. Phosphate

2. Pyramidines

3. Purines

4. Deoxyribose

5. Ribose

DNA is composed of two building blocks ______?

1. The bases (Adenine, Guanine, Cytosine, Thymine)

2. A Sugar-Phosphate backbone

Name the 2 major differences between DNA and RNA

1. RNA has Uracil, DNA has Thymine

2. The sugar is different in the Sugar-Phosphate backbone (Ribose for RNA, Deoxyribose for DNA)

Name 2 purposes of DNA

1. Repository for all information on synthesis of macromolecules and energy synthesis

2. Pass on information to the next generation

Name the 4 types of RNA and their functions

• mRNA (messenger RNA): Directs the synthesis of proteins.

• tRNA (transfer RNA): Adapter molecule between mRNA and amino acids in protein synthesis

• rRNA (ribosomal RNA): Structural component of a large complex of proteins and RNA known as ribosome. The ribosome binds to the mRNA and directs protein synthesis

• micro-RNA: Small, non-coding RNA involved in regulating the expression of specific regions of DNA. Others are part of large complexes that play specific roles in cell.

Amino acids have a common core repeating of _____

Amino-carbon-carboxyl groups with varying side chains on the central carbon.

Repeating backbone with an amino terminus and carboxyl terminus.

What are the 4 ways Amino Acids can be grouped?

1. Acid/Basic

2. Size, interactions with water

3. Specific element (contains sulphur)

4. Structure (contains rings)

Name 3 functions of lipids:

1. Energy Storage

2. Structural component of cell membranes

3. Participating as signaling molecules

What is this? And describe it

1. One type of lipid, known as a fatty acid, is composed of long chains of carbon molecules attached to a smaller head group.

2. The small head group is known as the polar head group.

3. The fatty acid chains are extremely hydrophobic and line up with the long chains of carbons near each other.

4. Because of the properties of the fatty acid chains, membranes are double-sided.

5. One side of a membrane is known as a leaflet. The polar head groups face the outside surfaces of the membranes because the polar head groups are water soluble.

6. Other chemical groups can be added to the head groups of the lipids but, in general, other chemical groups cannot be added to the fatty acids.

Name 3 functions of sugars

1. Immediate source of energy

2. Stored source of energy (long polymer of glucose called glycogen)

3. Structural components of the cell

Formula is (CH₂O)_n

Postulates of Cell Theory

• All living things are made of cells

• Smallest working units of all living beings

• Come from pre-existing cells through cellular divisiob

Define cell

The smallest unit that is capable of performing life functions

Explain the discovery of cells

Robert Hooke: discovered cells in cork slices. Why cork stoppers were so well suited to hold air in a bottle.

Anton van Leeuwenhoek: observed living cells in microorganisms. Observed “animalcules” that darted back & forth.

Matthias Schleiden: despite differences in structure of various tissues, plants were made of cells, plant embryo arose from a single cell.

Theodor Schwann: cellular basis of animal life. cells of plants & animals are similar structures

Both: argued that cells could arise from noncellular materials.

Name 5 characteristics of prokaryotes

• Simplest form of life

• No nucleus

• No membrane-bound organelles

• Few internal structures

• Unicellular

Name 5 characteristics of eukaryotes

• Most complex form of life

• Nucleus

• Membrane-bound organelles

• Most living organisms

• multicelluar

Name 14 differences between prokaryotes and eukaryotes

1. Typical organisms

2. Size (1-5µm for prokaryotes, 10-100µm for eu)

3. Nucleoid in pro, double-membrane nucleus in eu

4. Circular DNA in pro, linear molecules with histone proteins in eu

5. RNA + protein synthesis coupled in the cytoplasm in pro, RNA synth is nucleus, Prot synth in cytoplasm in EU

6. 50S, 30S ribosomes in pro, 60S and 40S in eu

7. Pro: very few cytoplasmic structures, EU: highly structured by membranes and a cytoskeleton

8. pro: flagella made of flagellin, EU: flagella containing microtubules, lamellipodia, and filopodia containing actin

9. Pros have no mitochondria, eu have 1-1000

10. pros ahve no chloroplasts, plants and algae do

11. pros are usually single cells, eu may be single celled, colonies, higher multicellular with specialized cells

12. pros divide by binary fissions, eus by mitosis/meiosis

13. pros have 1 chromosome, eus have multiple

14. pros only have cell membrane, eus have membrane bound organelles

Human cell size (egg, nerve, muscles)

• Most range from 10 - 15 µm in diametre

• Egg cells 100µm

• Nerve cells 1m long, muscle cells 30cm long

Bone cells (2)

• Robust body cell system and bound together by calcium and phosphate.

• Provide strength, support, and framework to the body by enclosing organs

Cartilage cells (chondrocytes) (3)

• surrounding material is loose and flexible compared to bone cells

• Freely bendable

• Present in ear bone, in between ribs and joints

Nerve cells(5)

They form what, structure, reproduction, location

• Form the nervous system

• very long and have many branches

• They never multiply or divide

• present all over the body and sometimes 1m long

• found in brain and spinal cord especially

Epithelial cells (3)

What they do

• Very simple cells which form the covering of other cells

• Form covering layers of all organs

• Also cover essential structures like nephrons in kidney which infiltrate blood

Muscle Cells

Name the alt name, what they’re rich in, structure, and types

• Also called myocytes

• Rich in proteins like actin and myosin due to which they contract

• Mostly long, large, provide movement to body

• Three types:

• Skeletal muscle cells: attached to long bones and assist in movements by contraction

• Cardiac Muscles: Present only in heart muscles and for heartbeats. Striated but branch

• Smooth muscle cells: flexible, yet contract and relax and present in the intestine, blood vessel helps movement of food through the gut

• Muscle cells store glucose through which they generate energy/heat

Secretory cell

function, example

• form glands and secret

• pancreatic cells secret insulin, sebaceous gland secrete oil on the skin

Adipose cells (3)

location, function

• Fat cells and sites where fat is stored

• in soles, palms

• Reduce friction to the body

Blood cells

reproduction, examples, function, lifestyle

• RBC, WBC, Thrombocytes

• Always motile

• Never multiply to form new cells; limited lifespans

Name the 5 types of cells based on function

1. Conductive Cells: Conduct an electric impulse from one region to another (e.g. muscle or nerve cells)

2. Connective cells: They help connect other cells (e.g. bone cells, blood cells)

3. Glandular cells: Secrete things. They form glands like the pancreas and salivary glands and produce enzymes, hormones.

4. Storage cells: Store fats and others for later use. This fat is consumed in starvation/ freezing temps. (e.g. adipose cells, some liver cells)

5. Supportive cells: Act in support for adjacent cells. (e.g. Glial cells in the brain provide nourishment to nerve cells and protect from trauma)

What are the 9 types of special cells?

1. Sperms: have haploid DNA. Present only in men. Have a tail to swim/move. Ezyme hyaluronidase penetrates uterine tissue and into reach oocytes

2. Oocytes: Haploid, present in women. Form from puberty to late menopause

3. Stem cells: primary/parent cells which differentiate into any required cell. Importance in treating disorders

4. Rods/cones: In eye, capture color and light

5. Ciliated cells: lining of respiratory tract, esophagus, have pointed thread which move in 1 direction to pass material.

6. Blood cells: RBCs, WBCs, platelets

7. Pancreatic cells: Both exocrine and endocrine cells

8. Hepatocytes: 80% of liver mass. Synth of proteins, carbs, fats, an breakdown of toxins/drugs. Large cells, have many mitochondria, /endoplasmic reticulum

9. Kupffer cells: In liver, macrophage action. Destroy old RBCs.

What are the sizes of bacteria and animal/plant cells? With examples

Bacteria: 0.5-10µm

Plant/Animal cells: 50-100 µm in size

Examples:

• E. coli: 2µm

• Amoeba 400µm

What are the evolutionary advantages of being large, long, and small?

Large:

Can compartmentalize functions

Long:

Single nucleus maintains control over long distance

Can conduct fluids/signals unobstructed

Small:

Large surface area to volume ratio

Diffusion time to cell center is low

How many neurons do human and mouse brains have?

•human brain: 86 x 10⁹  neurons

•mouse brain: 15 x 10⁹ neurons

What are the artificial, natural, and phylogenetic modes of classification?

Artificial:

• Habit, habitat, color, or occurrence.

• Aristotle organized them into aquatic, terrestrial, and aerial

  Natural:

• Morphology, cytology, phytochemistry, embryology, anatomy

• Homology is considered. e.g. forearm of vertebrates has the same pentadactyl structure but adapts differently

  Phylogenetic:

• Based on evolutionary descent and relationship

Archaea:

• shape?

• size?

• multiplication?

• respiration?

• nutrition?

• temperature?

• relationship to ecology?

• spherical, rod, spiral, lobed, plate or irregularly shaped, or pleomorphic

• 0.1 - 15µm, grows up to 20µm

• binary fission, budding, fragmentation,

• aerobic, facultatively anaerobic, or strictly anaerobic

• chemolithoautotrophs to organotrophs

• mesophiles or hyperthermophiles

• Some are symbionts

Bacteria

• cell wall?

• what do their proteins lack?

• describe their nucleic acids

• nutrition?

• petidoglycan

• proteins lack histones

• extrachromosomal DNA is present in the form of a plasmid

• transfer-messenger RNA

• asexual reproduction

• chemoautotrophs, heterotrophs

1. Fungal cell is encased in _____.

2. They reproduce _______.

3. They are ______ with _______, no ______.

4. body is called ________.

5. Most grow in the form of _______ which is either ______ or _______.

1. cell wall of chitin

2. budding, transverse division or spore formation (both asexual + sexual)

3. spore-bearing, absorptive nutrition, chlorophyll

4. thallus

5. hyphae, septate or aseptate

Algae do not represent a ______-

monophyletic group, 18S rRNA analysis has shown

3 characteristics of algae, 3 of their distribution

Characteristics of algae:

1. eukaryotic organisms that have chlorophyll, produce oxygen through photosynthesis

2. lack vascular conducting system

3. simple reproductive structures

Distribution:

1. water (marine, fresh water, or brackish)

2. suspended (planktonic) or living on bottom (benthic)

3. few algae live in the water-atmosphere surface and are termed neustonic

Protozoa

1. Name their important groups

2. what are they?

3. where do they grow?

1. flagellates, amoeba, sporozoan, ciliates

2. motile, eukaryotic, unicellular protist

3. free-living and parasitic

What were Robert Hooke’s accomplishments?

English microscopist

why were cork stoppers so well-suited to hold air?

called the pores cells

What were Leeuwenhoeks’s accomplishments?

Examined pond water under microscope

called them animalcules

What were Schawnn and Schleiden’s accomplishments?

Schwann:

• cellular basis of animals

• cells of plants and animals similar

Schleiden:

• plants were made of cells

  BUT they argued cells could arise from non-cellular stuff

What were Virchow’s accomplishments?

cells did not arise by spontaenous generation

What is modern cell theory?

• All organisms are composed of one or more cells

• The cell is the structural unit of life

• All cells come from pre-existing cells

What are the 9 properties of cells?

1. Complexity: cells are complex and organized

2. Genes: They possess genetic material and the means to pass it on

3. Reproduction': They can reproduce themselves

4. Energy: They acquire and utilize energy

5. Metabolism: They carry out chemical reactions

6. Mechanical activities: engage in mechanical activities

7. Sensitivity: Respond to stimuli

8. Homeostasis: They self-regulate

9. Adaptation: they evolve

What are the 9 similarities between eukaryotes and prokaryotes?

1. Plasma membrane of a similar construction

2. DNA encoded using identical genetic code

3. Similar mechanisms for transcription and translation including similar ribosomes

4. Shared metabolic pathways (TCA cycle, glycolysis)

5. Similar apparatus for conservation of chemical energy as ATP (plasma membrane for prokaryotes and mitochondrial membrane for eukaryotes)

6. Similar mechanism of photosynthesis (cyanobacteria and green plants)

7. Similar mech for synthesizing and inserting membrane proteins

8. proteasomes of a similar construction (b/w archaebacteria and eukaryotes)

9. cytoskeleton filaments similar to actin and tubulin

Define nucleus (6)

• Latin word from nuculeus meaning kernel

• Double-membrane bound organelle present in eukaryotic cells

• Constitutes most of the genetic material of the cells

• Maintains the integrity of the genes

• Regulate gene expression

• Known as the control center of the cell

How many nuclei in a cell?

Can be uni-nucleate

bi-nucleate

multi-nucleate

Name 3 characteristics of a nucleus

1. Bound by a double-membrane called the nuclear envelope.

2. Houses chromosomes. When the cell is not dividing, chromosomes are entangled in long structures called chromatin

3. Like the cell membrane, the nuclear envelope consists of phospholipids that form a lipid bilayer. It prevents back passage of molecules

What are the dimensions of the nucleus?

10% of the volume of the cell

6 micrometers in diameter

Semi-fluid matrix nucleoplasm similar in composition to the cytoplasm

What is between the 2 layers of a nuclear membrane?

Fluid-filled space or perinuclear space

How does a nucleus communicate with the cell?

Nuclear pores

Sites of exchange for large molecules like proteins

about 9nm wide

ATP, water, and ions permitted freely

Large molecules like proteins pass through active transport

Nuclear pores are composed of what?

Nucleoproteins

What is the nucleoplasm? (8)

• Gelatinous substance inside nuclear envelope. Also called karyoplasm

• Semi-aqueous material

• composed mainly of water with dissolved salts, enzymes, and organic molecules suspended within

• Nucleolus and chromosomes are surrounded by nucleoplasm

• Functions to cushion and protect the contents of the nucleus

• Nucleoplasm also supports the nucleus by helping to maintain its shape

• Nucleoplasm provides a medium by which materials, such as enzymes and nucleotides (DNA and RNA subunits), can be transported throughout the nucleus

• Nuclear pores exchange substances from nucleoplasm to cytoplasm

Nucleoli are formed around the ______

nuclear organizer regions

The nucleolus is not surrounded by a _____

membrane

What is the function of the nucleolus?

Helps to synthesize ribosomes by transcribing and assembling ribosomal RNA subunits. These subunits join together to form a ribosome during protein synthesis.

during cell division, the nucleolus _____

disappears/dissolves

Studies suggest that the nucleolus may be involved in _______

cellular aging and senescence

The nucleolus is composed of ________

proteins and RNA. Transported to the cytoplasm and attached to the ER

The nucleolus contains ________

nucleolar organizers

Parts of chromosomes with genes of protein synthesis on them

Nucleus regulates the synthesis of proteins in the cytoplasm through

mRNA. It is a transcribed DNA that serves as a template for protein production

During cell division the chromatin forms ______

well-defined chromosomes

What are chromosomes?

strings of DNA and histones (protein molecules) called chromatin

What are the two classifications of chromatin?

Heterochromatin:

• Highly condensed,

• transcriptionally inactive form,

• mostly present adjacent to the nuclear membrane

Euchromatin:

• delicate, less condensed organization of chromatin,

• which is found abundantly in a transcribing cell.

What are histones? (6)

• Highly alkaline proteins

• found in eukaryotic cell nuclei

• package and order the DNA into structural units called nucleosomes.

• They are the chief protein components of chromatin,

• acting as spools around which DNA winds, and

• playing a role in gene regulation

What do nucleosomes look like?

“beads on a string”

The string is DNA, and each bead is a “nucleosome core particle” that consists of DNA wound around a protein core formed from histones

How is the structural organization of the nucleosome discovered?

1. isolating them from unfolded chromatin by nucleases that break down DNA by cutting between nucleosomes

2. linker DNA is degraded

Each individual nucleosome core particle consists of a ________

complex of eight histone proteins

Two molecules each of histones

• H2A,

• H2B,

• H3, and

• H4—

• and double-stranded DNA

What is the structural organization of a nucleosome?

• The histone folds first bind to each other to form H3–H4 and H2A-H2B dimers

• The H3–H4 dimers combine to form tetramers

• A H3–H4 tetramer then further combines with two H2A-H2B dimers to form the compact octamer core,  around which the DNA is wound

Make new flashcard about diagram

Plasma membrane vs other membranes

Plasma membrane: separate the cell from its environment

Other membranes:

boundaries of other organelles and matrix for other chemical reactions

Name the 8 organelles that have no membrane

1. Ribosomes

2. Centrosomes/centrioles

3. Flagella/cilia

4. Microtubules

5. Basal bodies

6. Microfilaments

7. Cell Wall

8. Cajal bodies

Name the 3 double membrane organelles

1. Nuclei

2. Mitochondria

3. Chloroplasts

Name 5 single membrane organelles

1. lysosomes

2. peroxisomes

3. golgi bodies

4. vacuoles

5. endoplasmic reticulum

History of the plasma membrane

1880s: Overton

Dissolving power of the outer boundary layer of the cell matched that of a fatty oil.

1925: Grendel and Gorter

Amount of surface area covered by lipid when spread over the surface of water, 2:1.

1920s: Davson

Lower surface tensions of membranes than those of pure lipid structures

History of plasma membrane models

1. lipid nature of cell membrane

2. orientation of polar lipid molecules

3. amphipathic lipids form a bilayer

4. proteins are associated to the cell membrane

5. dark-clear-dark pattern universal

6. transmembrane molecules

Fluid Mosaic Model

mosaic of phospholipids, cholesterol, proteins, and carbohydrates

What sort of forces underly the plasma membrane bilayer?

• electrostatic

• van der Waals

• non-covalent

• hydrogen bonds

• hydrophilic and hydrophobic layers doesn't allow nucleic acids, amino acids, proteins, carbohydrates, and ions to pass through the bilayer

What is annular lipid shell?

Fraction of the lipid in direct contact with integral proteins which is tightly bound to the protein surface is called annular lipid shell

What is the consequence of unsaturated fats bending?

• prevents fatty acids from packing together

• decreasing the melting temperature

• increasing fluidity of the membrane

What is homeoviscous adaptation?

Ability of some organisms to regulate the fluidity of their cell membrane by altering their lipid composition

What are the three types of membrane lipids?

1. Phosphoglycerides

2. Sphingolipids

3. Cholestrol

Membranes: What is fluidity determined by?

• content of unsaturated fats (liquids at room temp)

• chain length (shorter chains more fluid)

What are Phosophoglycerides?

1. Glycerol-based lipids which have a glycerol backbone

2. phosphatidic acid like

3. cardiolipin

4. phosphatidylcholine

What are sphingolipids?

• Amino alcohol

• Contains two long hydrocarbon chains

• sphingosine linked to a fatty acid by its amino acid, ceramine

• additional groups esterified to the terminal alcohol of the sphinosine moeity

Fatty acyl chains of sphingolipids, however, tend to be longer and more highly saturated than those of phosphoglycerides

Why is Cholesterol important? (4)

• present in almost the same proportion as phospholipids

• amphipathic

• makes cell membrane more rigid and prevents membrane being too fluid

• hydrophobic regions prevent ions and polar molecules passing, esp in neurons

Lipid anchored proteins

• covalently bound to one or more lipid molecules

• hydrophobically insert into the cell membrane and anchor protein

• protein itself not in contact with membrane

e.g. G protein

Peripheral protein

• attached to integral membrane proteins

• peripheral regions of lipid bilayer

e.g. enzymes and hormones

Name 6 functions of glycolipids

1. Cell-to-Cell recognition in eukaryotes

2. Located on cell surface where they host cells and share information

3. Viruses that bind to cells using these receptors cause an infection

4. Glycosylation (carbohydrate is covalently attached to a target macromolecule) occurs on extracellular surface

5. (glycocalyx) dense, gel-like meshwork that surrounds the cell, constituting a physical barrier for any object to enter the cell.

6. participates in cell adhesion, lymphocyte homing

What are the 4 main functions of glycoproteins

1. Act as channels: Na+/K+ pump to maintain ion concentrations on either side of membrane

2. Transporters: identify and attach to specific substances e.g. nutrients

3. Enzymes:

4. Receptors: recognize and bind to target molecules

3 primary functions of biological membranes

1. keep toxic substances out of the cell

2. separate vital but incompatible metabolic processes within organelles

3. receptors and channels let molecules pass through

Secondary functions of cell membrane

1. Anchors the cytoskeleton: gives shape to cell, protects organelles and works as an enclosure

2. Cellular transport

3. Attaching to extracellular matrix so cells can group together

4. Communication with other cells: protein molecules receive signals and convert to messages that are passed to organelles

5. Undertake metabolic activites: group together to form enzymes

Name the 5 types of gates

1. ungated: some K+ gates are always open

2. voltage-gated:

3. ligand-gated: regulatory molecules bind to channel protein. e.g. neurotransmitter receptors

4. mechanically-gated

5. temperature-gated

History of mitochondria

• Altman identified Mitochondria

• Carl Benda named them

• Philip named them powerhouse of cell

Describe the structure of mitochondria

• It has an outer membrane that covers it like a cell

• Inner membrane folds over many times and is named cristae (creates more surface area so more space for reactions to occur)

• Fluid in the cristae is called matrix

• Mitochondria are special because they have their own ribosomes and DNA in the matrix

• Granules control concentration of ions

Production of mtDNA

• encodes 37 genes in humans

• inherited from the mother

• significant portion of first human sequences

Using oxygen to release energy

• Proteins take organic molecules like pyruvate and Acetyl CoA and chemically digest them.

• Proteins embedded in the inner membrane and enzymes involved in the citric acid cycle release water and CO2 from the breakdown of oxygen and glucose.

Outer membrane of mitochondria

• Is smooth unlike the inner membrane and has almost the same amount of phospholipids and proteins

• Large number of special proteins called porins

• Allow molecules of 5000 daltons or less to go through

• It is completely permeable to ADP, ATP, nutrient molecules, ions

Inner membrane of mitochondria

• permeable only to Carbon Dioxide, water, oxygen

• contains the complexes of the electron transport chain and the ATP synthase complex

• large number of proteins that play an important role in producing ATP

• also helps in regulating transfer of metabolites across the membrane

• infoldings called the cristae that increase the surface area for the complexes and proteins that aid in the production of ATP, the energy rich molecules

Mitochondria Matrix

• complex mixture of enzymes that are important for the synthesis of ATP molecules, special mitochondrial ribosomes, tRNAs and the mitochondrial DNA

• oxygen, carbon dioxide and other recyclable intermediates

• Originated through endosymbiosis (due to independent DNA and similarities to bacteria)

• reproduce through fission