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biosci > Introduction to cells > Flashcards

Introduction to cells Flashcards

1
Q

What is cell theory

A
  1. All organisms are composed of one or more cells
  2. The cell is the basic unit of structure and organisation
  3. All cells arise from pre-exisiting cells
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2
Q

The central dogma

A

DNA -> RNA -> Protein

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3
Q

Similarities between prokaryote and eukaryotic cells

A

Both have:
Plasma membrane, cytosol, DNA, RNA, protein and ribosomes

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4
Q

Difference between prokaryote and eukaryote cells

A

Eukaryotic have membrane-bound organelles while prokaryote doesn’t. Eukaryote cells are also much larger.

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5
Q

What is the cytoplasm

A

Everything inside the plasma membrane including the organelles, but not including the nucleus

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6
Q

What is the cytosol and what does it include

A

The fluid portion of the cytoplasm, which includes water plus dissolved and suspended substances

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7
Q

What is part of the endomembrane system

A

Nucleus, endoplasmic reticulum (smooth and rough), Golgi apparatus, and lysosomes

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8
Q

What is the function of the endomembrane system

A

Package, label and ship molecules

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9
Q

What is the plasma membrane

A

A selectively permeable barrier controlling the passage of substance in and out of the cell

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10
Q

What is the structure of the plasma membrane

A

Double layer of phospholipids with embedded proteins.

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11
Q

What do phospholipids consist of

A

Hydrophilic polar heads (phosphate)
Hydrophilic lipid tails (fatty acids)

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12
Q

How are phospholipids arranged as

A

Arranged as a double layer around cytoplasm, tail to tail

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13
Q

What are two functions of plasma membrane proteins

A

Mediate movement of hydrophilic substances. Allow cell identification and facilitate intercellular movement

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14
Q

True of false, plasma membrane proteins are often amphipathic

A

True, they contain both hydrophilic and hydrophobic regions

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15
Q

Plasma membrane - Integral proteins

A

Embedded (partially or fully) in the membrane

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16
Q

What are peripheral membrane proteins of the plasma membrane

A

Associated with the membrane, but not actually embedded in it.

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17
Q

What are the six key functions of plasma membrane proteins

A

a) transport
b) enzymatic activity
c) signal transduction
d) cell-cell recognition
e) intercellular joining
f) attachment to the cytoskeleton and ECM

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18
Q

What are examples of transport of plasma membrane proteins

A

Channels, transporters, may be general or selective, gated or not

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19
Q

What is enzymatic activity (b)

A

Carry out chemical reactions, may or may not be a part of a team of enzymes

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20
Q

What is signal transduction (c)

A

External signalling molecule causing communication of information to the inside of the cell

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21
Q

What is cell-cell recognition (d)

A

Use of glycoproteins (carbohydrate + protein) as molecular signatures of the extracellular side of the cell

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22
Q

What are examples of intercellular joining as a function of PM proteins (e)

A

Gao junctions or tight junctions

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23
Q

What are examples of the attachment to the cytoskeleton and ECM as a function of PM proteins (f) and what do they do

A

Fibronectin mediates contact between cell surface integrins and ECM (e.g collagen)
Can facilitate movement

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24
Q

Are membranes static or not, and why

A

No, the membrane is a mosaic of molecules bobbing in a fluid bilayer of phospholipids.
Is cell specific and dynamic repertoire of membrane-bound proteins present as required

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25
Q

What is the structure of the nucleus

A

Enclosed by double lipid bilayer called the nuclear envelope continuous with rough ER

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26
Q

What are two functions of nuclear pores

A

Regulate the movement of substances as enter and exit the cell (e.g proteins and mRNA). They protect DNA, so DNA doesn’t change or get replaced

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27
Q

What is the the function of the nucleolus

A

Used for rRNA production and the assembly of small and large subunits of ribosomes

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28
Q

What does molecule segregation allow for in the nucleus

A

Temporal and spatial control of cell function

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29
Q

What is the structure of the nucleosome

A

DNA wrapped twice around a group of 8 histones, collectively known as a chromatin

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30
Q

The function of chromatin as preparation for cell division

A

Chromatin condenses to form chromatin fibres then condenses further into loops which stack as chromosomes

31
Q

What form does DNA spend most of its time as

A

Chromatin and chromatin fibres

32
Q

What is the structure of ribosomes

A

Two subunits; small and large, made of ribosomal RNA (rRNA) in complex with many proteins

33
Q

What is the function of ribosomes

A

Protein production (translation)

34
Q

Where are the two places in the cell where ribosomes are found

A

Cytoplasm and the rough ER

35
Q

Where are free ribosomes found and what is their function

A

In the cytoplasm
Make proteins to be used in cytosol

36
Q

Where are attached/bound ribosomes found and what is their function

A

Found in the RER - Making non-cytosolic proteins/endomembrane

37
Q

What is the endoplasmic reticulum and where is it located

A

An extensive network of tubes and tubules, stretching from the nuclear membrane.

38
Q

What is the major function of the Rough ER - three products

A

Production of:
Secreted proteins
Membrane proteins
Organelle proteins

39
Q

Structure and location of Rough ER

A

Continuous with nuclear envelope dotted with attached ribosomes

40
Q

The proteins enter ____ within the rough ER for folding

A

The lumen

41
Q

The rough ER membrane surrounds the protein to form _______ destined for Golgi

A

Transport vesicles

42
Q

What is the function of smooth ER

A

Functions vary greatly from cell to cell, but its major function:

A housing unit for proteins and enzymes (e.g in the liver it houses enzymes for detoxification and glucose release and in the muscle it stores calcium ions).

Synthesises lipids, including steroids and phospholipids and storage of cell-specific proteins.

43
Q

Does the smooth ER make proteins?

A

No it doesn’t make proteins, it lacks proteins

44
Q

Where is the smooth ER found

A

It extends from the rough ER

45
Q

What is the function of the Golgi apparatus

A

Modify, sort, package and transports proteins received from the rough ER using enzymes in each cisternae

46
Q

What is the structure of the Golgi apparatus

A

Made up of 3-20 flattened membranous sacs called cisternae, stacked on top of each other.

47
Q

The Golgi apparatus is responsible for the formation of what?

A

Secretory vesicles (proteins for exocytosis)

Membrane vesicles (PM molecules)

Transport vesicles (molecules to lysosomes)

48
Q

What does each sac or cisternae of the Golgi apparatus contain

A

Enzymes of different functions

49
Q

Movement of proteins in Golgi apparatus

A

Proteins move cis to trans from sac to sac
Mature at exit cisternae
Travel to destination

50
Q

What occurs in each sac/cisternae of the Golgi apparatus

A

Modifications (formation of glycoproteins, glycolipids, and lipoproteins)

51
Q

What are lysosomes

A

Vesicles formed from the Golgi apparatus

52
Q

What do lysosomes contain

A

Powerful digestive enzymes

53
Q

What do membrane proteins do in the lysosome

A

Pump H+ to maintain acidic pH.

54
Q

What is the main function of lysosomes

A

Digestion of:
- substances that enter a cell
- cell components (e.g organelles) - autophagy
- entire cells (autolysis)

55
Q

What happens once the food has been digested in the lysosomes

A

Once digested, all building blocks (amino acids, lipids etc.) are recycled

56
Q

What is the main function of the mitochondria

A

Generate ATP through cellular respiration

57
Q

What is the mitochondria made up of

A

Outer mitochondrial matrix

Inner mitochondrial matrix, with folds called cristae

Fluid-filled interior cavity, called the mitochondrial matrix

58
Q

When would a greater number of mitochondria need to be present

A

When a cell requires more energy, so the more ATP is makes and requires more mitochondria

59
Q

What kind of DNA does mitochondria have

A

Carries a separate small (37 genes) genome encoding mitochondrial specific products

60
Q

What is the cytoskeleton and what is it’s function

A

The structural support system of the cell. Acts as scaffolding of the cell and involved in intracellular transportation and cell movement

61
Q

What does the cytoskeleton contain that helps it carry out its function

A

Fibres or filaments that help to maintain the size, shape and integrity of the cell

62
Q

What the three types of fibres in the cytoskeleton from smallest to largest

A

Microfilaments
Intermediate filaments
Microtubules

63
Q

What is the microfilaments comprised of (in the cytoskeleton) and where is it found

A

Actin molecules assembles in two long chains, twisted around each other. It’s found around the periphery and lining of the cell interior

64
Q

Function of the microfilaments in the cytoskeleton

A

Bear tension and weight by anchoring cytoskeleton to plasma membrane proteins, and promote amoeboid motility if required.

65
Q

Are microfilaments dynamic and why

A

Yes they are, they can assemble and disassemble as required, so not static

66
Q

What is the intermediate filaments of the cytoskeleton comprised of and what is its function

A

Diverse range of materials, including keratin - which allows organisms to lean on and scaffold

67
Q

What is the function of the intermediate filaments of the cytoskeleon

A

Bear tension and weight throughout cell e.g during cell anchoring

Act as scaffold for cellular organelles e.g the nucleus

68
Q

Where are intermediate filaments of the cytoskeleton found

A

In the cytoplasm of the cell

69
Q

Which one of the three fibres of the cytoskeleton is the most permanent, and why

A

Intermediate filaments, because they are less dynamic

70
Q

What is the microtubules of the cytoskeleton comprised of

A

Tubulin dimers (alpha and beta), coiled, to form a tube.

71
Q

Where are microtubules of the cytoskeleton found

A

Extended from the centriole an cytoplasm/nucleus

72
Q

What is the function of the microtubules of the cytoskeleton

A
  • Support cell shape and size
  • Guide for movement of organelles
  • Chromosome organisation
  • Support and movement of cilia/flagella
73
Q

Are microtubules dynamic, and why

A

Yes, they can assemble and disassemble when needed

biosci (28 decks)

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