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Cell Biology Flashcards

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1
Q

What does the plasma consist of?

A

Bilayer mostly phospholipids

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2
Q

What does the plasma membrane do?

A

Separates a cell from its environment
Proteins allow communication with external environment- selective permeability
Fluid mosaic model- mobility of components of the membrane

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3
Q

What does membrane flexibility allow?

A

Cell growth and cell movement

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4
Q

What is a phospholipids?

A

Two fatty acid chains and glycerol + phosphate group

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5
Q

What are amphipathic?

A

Molecules that have both hydrophilic and hydrophobic properties

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6
Q

What is the lipid bilayer?

A

A 2D fluid, consisting of phospholipids

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7
Q

What do membrane proteins do?

A

Transport nutrients, metabolites and ions across the lipid.

Some work as enzymes catalysing reactions

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8
Q

What do anchor proteins do?

A

Anchor the membrane to macromolecules

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9
Q

What do receptor proteins do?

A

Detect chemical signals in the environment and transmit them to the cell interior

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10
Q

Where are integral membrane proteins attached to?

A

Directly to a lipid bilayer

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11
Q

What are the different forms of transmembrane proteins?

A

Single alpha-helix, as multiple alpha- helices or as a beta-barrel

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12
Q

What are monolayer associated proteins anchored to?

A

The cytosolic surface via an amphipathic alpha helix

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13
Q

What is lipid-linked proteins attached to?

A

Either side of bilayer via a covalent attachment to a lipid molecule

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14
Q

What is a peripheral membrane proteins?

A

protein- attached-protein

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15
Q

How are protein-attached proteins attached to membrane?

A

By relatively weak, noncovalent interactions with other membrane proteins

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16
Q

What are main features of prokaryotes?

A

Little internal organisation

Much smaller than eukaryotes

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17
Q

What do eukaryotes contain what prokaryotes don’t?

A

DNA contained in nucleus
Membrane-enclosed organelles
Internal compartments for special functions

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18
Q

What is main features of the nucleus?

A

Contains DNA
Surrounded by a double-membrane envelope
Nuclear pores are gateway for molecules
Storehouse for genetic information

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19
Q

What is DNA packed with inside the nucleus?

A

Long polymers of DNA are packed with proteins into a small space

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20
Q

How many more times DNA can eukaryotes have than prokaryotes?

A

1000x

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21
Q

What does the endoplasmic reticulum do?

A

Interconnected tubes and flattened sacs
Rough ER- ribosomes, makes membrane secreted proteins. Proteins then fold, assemble with other proteins and form disulphide bonds and enhanced with oligosaccharides chains.
Smooth ER- makes membrane vehicles and lipids

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22
Q

What is the ER continuous with?

A

The membrane of the nuclear envelope

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23
Q

What are vesicles and what do they do?

A

Membrane-enclosed sacs

Transport vehicles- moving substances from one location to another

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24
Q

What is the Gogi apparatus?

Study These Flashcards
A

Stacked, flattened membrane sacs.
Processes new proteins and lipids. It adds specific chemical groups to molecules made in the ER and targets them to their destination

25
What are flattened membrane-enclosed sacs called?
cisternae
26
How many cisternae does each stack contain?
3-20
27
What are the two faces that yogi stack has?
cis-face: entry face- adjacent to the ER | Trans face: exit face- points towards the plasma membrane
28
What mediates the transport of proteins from the ER to the Gogi?
Transport vesicles that bud off form one mbrane and fuse with another membrane- vehicular transport
29
What does the yogi send molecules to?
From trans Gogi network to the plasma membrane, lysosomes for degradation or secretory vesicles
30
What is constrictive exocytosis?
The process in which : Transport of vesicles perpetually bud form the trans Gogi network and fuse with the membrane
31
What are lysosomes?
Small spherical organelles Contains enzymes to break down macromolecules Release simple sugars, amino acids and fats to be recycled. To clear cell of damaged organelles, as a source of food, to destroy invading bacteria
32
What is a endosome?
A membrane-enclosed compartment of a eukaryotic cell through which endocytosed material passes on its way to lysosmes
33
What is the vacuole?
A specialised structure in plants and fungi Breaks down substances Stores chemicals for later use Fills with water to provide rigidity
34
What are mitochondria?
Double-membrane organelle Inner membrane folded into cristae Harnesses energy form chemical breakdown Cellular respiration- produces ATP
35
Does mitochondria contains its own DNA?
Yes and reproduce by dividing in two
36
What are chloroplasts?
Double-membrane organelle Contains grana made of thylakoids Converts CO2 and H20 into sugar using light Chlorophyll enables photosynthesis
37
How many mitochondria does a liver cell have?
Approx.. 1700
38
What is the cytoplasm?
All the contents of the eukaryotic cell, excluding only the nucleus
39
What are the content of eukaryotic cell divided between?
cytosol and the organelles
40
What are peroxisomes?
small organelle present in the cytoplasm of many cells, which contains the reducing enzyme catalase and usually some oxidases.
41
What does the cytoskeleton provide?
Gives cell its shape Provides internal support Is responsible for movement
42
What are microtubules?
The thickest cytoskeletal element A helical polymer of tubulin monomers Grow or shrink by adding or losing monomers
43
What the microtubules based movement?
Microtubules radiate out form the centre | Used as tracks for vehicle movement
44
What are some other cytoskeleton components?
Intermediate filaments | microfilaments
45
What do intermediate filaments do?
Ropelike filament | Provides structural support
46
What do microfilaments do?
Smallest diameter Made of actin monomers Involved in cell crawling- pseudopodia project forward and pull the cell
47
What is the difference between cilia and flagella?
Cilia beat in unison like oars | flagella beat like whips- waves pass down the length of a eukaryotic flagellum to generate motion
48
What causes motion of bacterial flagella?
Very different from eukaryotic flagella H+ ions pumped out of cell H+ ion entry causes the motion Flagellum rotates like a propeller
49
How many microtubules does eukaryotic flagella and cilia have?
9 microtubules pairs surrounding 2 central microtubules in cross section
50
How does eukaryotic cilia or flagella move?
ATP allows dynein molecules attached to one microtubules pair to go down the other microtubules pair, causing the flagella or cilia to bend
51
What does microtubules transport along a nerve cell axon?
Cargo
52
What move along microtubules?
Motor proteins using their globular head. | Two types: kinesins and dyneins
53
What do kinesins do?
move towards the plus end of a microtubule (away form the cell centre)
54
What do dyneins do?
move towards the minus end
55
What are both kinesins and dyneins?
They are dimers with 2 globular ATP binding heads and a tail. ATP dependent movement. They transport cargo.
56
What do microtubules and motor proteins have an important role in doing?
positioning membrane- enclosed organelles within a eukaryotic cell
57
Where did eukaryotic cells most likely evolve from?
Prokaryotes- larger prokaryotes ingested smaller prokaryotes Or free-living mitochondria and chloroplasts were captured- formed an endosymbiotic relationship with the host cell
58
Where did mitochondria most likely evolve form?
Engulfed bacteria that were engulfed by an ancestral eucaryotic cell and survived within it, in a symbiotic relationship with the host
59
What did chloroplast most likely evolve from?
Engulfed bacteria symbiotic photosynthetic bacteria which were taken up by eucaryotic cells that already possessed mitochondria

Biosciences (6 decks)

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