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The eukaryotic cell (lectures 1-4) Flashcards

1
Q

What is cell biology?

A

The study of the structures, functions and behaviours of cells

A cell is always derived from another cell

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2
Q

What is the LUCA?

A

Last Universal Common Ancestor

All life forms on earth can be traced back to a LUCA, a single cell organism

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3
Q

Features of eukaryotic cells

A

Highly compartmentalised

Complex end-membranes and cytoskeleton

Are chimeras - cellular and genomic

Share an ancestor that possessed a bacterial endosymbiont that evolved into modern mitochondria

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4
Q

What do phylogenic trees show?

A

Evolutionary history of a group of organisms
Inferred directly from nucleotide or amino acid sequence data
Certain genes are globally distributed

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5
Q

What is the most widely used phylogenic marker?

A

Small subunit ribosomal RNA (SSUrRNA) gene

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6
Q

What are the 2 types of membranes?

A

Endogenous

Exogenous

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7
Q

Examples of endogenous membranes

A

RER

Nucleus

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8
Q

Examples of exogenous membranes

A

Mitochondria

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9
Q

What is the archezoa hypothesis?

A

Archezoa is a kingdom proposed for eukaryotes that diverged before the origin of mitochondria

First eukaryotes were anaerobes

Nucleus was invented before the mitochondria was acquired

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10
Q

When would the archezoa hypothesis fall?

A

Would fall if we find:

1) Archezoans branch among aerobic species with mitochondria
2) Mitochondrial genes on archezoan genomes
3) Mitochondria-derived organelles in archezoans

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11
Q

What does the plasma membrane do?

A

Encloses cell content
Separates it from the external environment
Allows different concentrations of substances to be maintained

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12
Q

What are endomembranes and what do they do?

A

Are complex internal membranes

Allow separate compartments to have different constituents and functions

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13
Q

What are biological membranes made of?

A

Lipid bilayers

Proteins

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14
Q

Function of the cytosol

A

Many metabolic pathways

Protein synthesis

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15
Q

Function of the nucleus

A

Contains main genome

DNA and RNA synthesis

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16
Q

Function of the endoplasmic reticulum

A

Synthesis of most lipids

Synthesis of proteins for distribution

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17
Q

Function of the golgi apparatus

A

Modification, sorting and packaging of proteins and lipids for either organelles, the PM or secretion

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18
Q

Function of the lysosomes

A

Intracellular degradation

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19
Q

Function of the endosomes

A

Sorting of endocytose material

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20
Q

Function of the peroxisomes

A

Oxidation of toxic molecules

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21
Q

Function of the mitochondria

A

Oxidative phosphorylation

FeS cluster biosynthesis

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22
Q

Function of the chloroplasts

A

Photosynthesis

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23
Q

Function of the plasma membrane

A

Barrier functions
Communication with environment and other cells
Passage of molecules in and out of cell
Cell growth, shape change, movement, division

24
Q

Cells integrate genotypes and the environmental cues to generate phenotypes.
What is deterministic and probabilistic?

A

Deterministic - penetrative gene mutation

Probabilistic - complex combination of genes and the environment

25
Most common lipids in eukaryotes
Phospholipids Cholesterol Glycolipids
26
What are glycolipids?
Sugar containing lipids Face away from the cytosol Localised to apical side of epithelial cells
27
Why is membrane fluidity important?
Needs to be precisely regulated to ensure survival of cell Lipid composition and temperature influence fluidity hugely Many organisms can adjust membrane composition in relation to the temperature of the environment
28
Functions of membrane proteins
1) Transporters 2) Linkers 3) Receptors 4) Enzymes
29
What is the glycocalyx?
The cell coat Protects against physical, chemical and biological damages
30
Functions of the glycolcalyx
1) Protection 2) Adhesion 3) Recognition 4) Storage
31
What is polarised distribution of proteins?
When proteins are restricted to specific domains of the membrane and cannot diffuse in the plane of the membrane
32
What are the 3 types of energy driven transport?
1) Coupled transport 2) ATP driven transport 3) Light or redox driven transport
33
What are the 3 major types of transport?
1) Gated transport 2) Transmembrane transport 3) Vesicular transport
34
Movement between the nucleus and the cytoplasm
Nucleur envelope surrounds the nucleus Nucleus pores • Allow small molecules to diffuse • Bigger molecules need specific transport molecules Through the nucleur pore complex (NPC)
35
What are the different types of protein translocators?
TOM - outer membrane | TIM - inner membrane
36
What happens to proteins once in the lumen of the RER?
Either: 1) Remain in the RER 2) Travel to other organelles 3) Export to cell surface or exterior to be secreted Vesicular transport dependent
37
What is vesicular transport essential for?
Cell survival | Reproduction
38
What is the golgi apparatus?
Located near the nucleus Pile of membrane stacks (cisternae) Polarised Inner cis face - vesicles from RER enter Outer trans face - export vesicles to organelles/PM
39
What happens within the golgi apparatus?
``` Further sugars added/removed Enzymes located in specific regions • Early acting - near cis face * Late acting - near trans face Proteins leave the golgi in membrane vesicles ```
40
What is autophagy?
Process of destroying internal components
41
Why is autophagy important?
Helps maintain health Homeostasis Important during normal cell growth and differentiation Adaptive responses to stress
42
What happens when autophagy goes wrong?
Dysfunctional autophagy | Associated with infectious disorders, neurodegenerative disease and cancer
43
What filaments is the cytoskeleton made of?
Intermediate filaments Microtubles Actin
44
What does the cytoskeleton do?
Responsible for cell shape and movement Positions organelles within the cell Directs transport between intracellular compartments
45
Intermediate filaments
In both the cytoplasm and the nucleus Provide mechanical strength Prevent excess stretching Diameter = 10 nm
46
What are nucleur lamins?
IF's in the nucleus Lines inner face of the nucleur envelop Attachment sites for binding proteins and chromosomes Breaks down during cell division • Assembly and disassembly regulated by phosphorylation
47
Microtubles
``` Move chromosomes during cell division Intracellular transport Drive cilia and flagella Rigid and unstable Diameter = 25 nm Made of tublin monomers Grow out from the organising centres • Centrosome - normal cells • Spindle poles - mitotic spindle • Basal body - cilia/flagella ```
48
How do microtubules assemble?
``` Assemble from dimers of alpha and beta tubulin Forms a cylinder of 13 protofilaments This forms a straw/tube Tubes are polarised • Grow from the positive end • Break down from the negative end ```
49
What are cilia?
Hair like extensions Short extensions Contain microtubules Can be mobile or stationary
50
What are microvilli?
Localised on the villi (lumen of the small intestine) Increase SA for absorption Extension of the plasma membrane Contain actin filaments to keep upright
51
Actin filaments
``` Thin and flexible Cell motility and contraction Maintain cell shape Made of actin monomers - use ATP to build Diameter = 6-8 nm Polar filament ```
52
How are actin filaments formed?
``` Filament is polarised Monomers of G-actin add to either end • More rapidly at the + end Polymerisation associated with ATP hydrolysis Regulated by actin binding proteins ```
53
Actin filaments motor proteins
Myosins Globular heads bind ATP Heads bind to actin filaments and hydrolysis of ATP drives movement Tails bind structures such as the PM, vesicles and other myosin molecules
54
What is spectrin?
``` A cytoskeletal protein Inner plasma membrane Mechanical strength, stability and shape Link membranes to the motor proteins Forms a scaffold ```
55
Diameter of cytoskeletal filaments
Intermediate filament = 10 nm Microtuble = 25 nm Actin filament = 6-8 nm

Cell biology (14 decks)

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