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Biosciences > Cell Biology > Flashcards

Cell Biology Flashcards

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?

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
Q

What are flattened membrane-enclosed sacs called?

A

cisternae

26
Q

How many cisternae does each stack contain?

A

3-20

27
Q

What are the two faces that yogi stack has?

A

cis-face: entry face- adjacent to the ER

Trans face: exit face- points towards the plasma membrane

28
Q

What mediates the transport of proteins from the ER to the Gogi?

A

Transport vesicles that bud off form one mbrane and fuse with another membrane- vehicular transport

29
Q

What does the yogi send molecules to?

A

From trans Gogi network to the plasma membrane, lysosomes for degradation or secretory vesicles

30
Q

What is constrictive exocytosis?

A

The process in which : Transport of vesicles perpetually bud form the trans Gogi network and fuse with the membrane

31
Q

What are lysosomes?

A

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
Q

What is a endosome?

A

A membrane-enclosed compartment of a eukaryotic cell through which endocytosed material passes on its way to lysosmes

33
Q

What is the vacuole?

A

A specialised structure in plants and fungi
Breaks down substances
Stores chemicals for later use
Fills with water to provide rigidity

34
Q

What are mitochondria?

A

Double-membrane organelle
Inner membrane folded into cristae
Harnesses energy form chemical breakdown
Cellular respiration- produces ATP

35
Q

Does mitochondria contains its own DNA?

A

Yes and reproduce by dividing in two

36
Q

What are chloroplasts?

A

Double-membrane organelle
Contains grana made of thylakoids
Converts CO2 and H20 into sugar using light
Chlorophyll enables photosynthesis

37
Q

How many mitochondria does a liver cell have?

A

Approx.. 1700

38
Q

What is the cytoplasm?

A

All the contents of the eukaryotic cell, excluding only the nucleus

39
Q

What are the content of eukaryotic cell divided between?

A

cytosol and the organelles

40
Q

What are peroxisomes?

A

small organelle present in the cytoplasm of many cells, which contains the reducing enzyme catalase and usually some oxidases.

41
Q

What does the cytoskeleton provide?

A

Gives cell its shape
Provides internal support
Is responsible for movement

42
Q

What are microtubules?

A

The thickest cytoskeletal element
A helical polymer of tubulin monomers
Grow or shrink by adding or losing monomers

43
Q

What the microtubules based movement?

A

Microtubules radiate out form the centre

Used as tracks for vehicle movement

44
Q

What are some other cytoskeleton components?

A

Intermediate filaments

microfilaments

45
Q

What do intermediate filaments do?

A

Ropelike filament

Provides structural support

46
Q

What do microfilaments do?

A

Smallest diameter
Made of actin monomers
Involved in cell crawling- pseudopodia project forward and pull the cell

47
Q

What is the difference between cilia and flagella?

A

Cilia beat in unison like oars

flagella beat like whips- waves pass down the length of a eukaryotic flagellum to generate motion

48
Q

What causes motion of bacterial flagella?

A

Very different from eukaryotic flagella
H+ ions pumped out of cell
H+ ion entry causes the motion
Flagellum rotates like a propeller

49
Q

How many microtubules does eukaryotic flagella and cilia have?

A

9 microtubules pairs surrounding 2 central microtubules in cross section

50
Q

How does eukaryotic cilia or flagella move?

A

ATP allows dynein molecules attached to one microtubules pair to go down the other microtubules pair, causing the flagella or cilia to bend

51
Q

What does microtubules transport along a nerve cell axon?

A

Cargo

52
Q

What move along microtubules?

A

Motor proteins using their globular head.

Two types: kinesins and dyneins

53
Q

What do kinesins do?

A

move towards the plus end of a microtubule (away form the cell centre)

54
Q

What do dyneins do?

A

move towards the minus end

55
Q

What are both kinesins and dyneins?

A

They are dimers with 2 globular ATP binding heads and a tail. ATP dependent movement. They transport cargo.

56
Q

What do microtubules and motor proteins have an important role in doing?

A

positioning membrane- enclosed organelles within a eukaryotic cell

57
Q

Where did eukaryotic cells most likely evolve from?

A

Prokaryotes- larger prokaryotes ingested smaller prokaryotes
Or
free-living mitochondria and chloroplasts were captured- formed an endosymbiotic relationship with the host cell

58
Q

Where did mitochondria most likely evolve form?

A

Engulfed bacteria that were engulfed by an ancestral eucaryotic cell and survived within it, in a symbiotic relationship with the host

59
Q

What did chloroplast most likely evolve from?

A

Engulfed bacteria symbiotic photosynthetic bacteria which were taken up by eucaryotic cells that already possessed mitochondria

Biosciences (6 decks)

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