Lecture 6: INTRO Cell structure and function Flashcards

1
Q

What is cell theory?

A
  1. All living 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 existing cells (via mitosis or meiosis)
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2
Q

What are the common features of prokaryotes and eukaryotes?

A

Both have cell surface plasma membrane
Have ribosomes
Have cytosol
Have DNA, RNA and protein

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3
Q

What are the differences between prokaryotes and eukaryotes

A

Eukaryotes have membrane bound organelles and are larger

Prokaryotes have no membrane bound organelles and are smaller

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4
Q

What is cytoplasm?

A

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

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5
Q

What is cytosol?

A

The fluid in the cytoplasm - composed of water and dissolved substances (ions, ATP, proteins, lipids)

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6
Q

What is the endomembrane system?

A

The organelles of a cell involved in packaging, labelling, and shipping molecules around the cell

Made up of:
Nucleus
ER smooth and rough
Golgi apparatus
Lysosomes
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7
Q

Plasma membrane function

A

The plasma membrane is a selectively permeable barrier controlling the passage of substances in and out of the cell

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8
Q

Plasma membrane structure

A

Double layer of phospholipids with embedded proteins

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9
Q

Phospholipid structure

A

Made up of a hydrophilic phosphate head and two hydrophobic fatty acid tails arranged as a tail to tail bilayer

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10
Q

What are integral proteins

A

proteins embedded partially or fully in the plasma membrane

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11
Q

What are transmembrane proteins

A

Type of integral protein that spans the whole membrane coming in contact with extracellular and cytoplasmic areas

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12
Q

What are peripheral membrane proteins

A

Associated with the membrane but not embedded in them

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13
Q

What is function of peripheral membrane proteins

A

Cell to cell identification and facilitate intercellular communication

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14
Q

What is function of integral proteins

A

Mediate movement of hydrophilic substances

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15
Q

What are 6 functions of plasma membrane proteins?

A
Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intracellular joining
Attachment to cytoskeleton and extracellular matrix
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16
Q

Nucleus function

A

House DNA in eukaryotic cells
Make RNA and assemble ribosomes
pores regulate movement of substances (protein and mRNA) in and out
molecule segregation to allow temporal and spatial control of cell function

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17
Q

Nucleus structure

A
The largest distinct structure in the cell
Made up of:
nucleolus
nuclear envelope
nuclear pores
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18
Q

What is nucleolus

A

Dark region of nucleus where rRNA are produced later forming ribosomes

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19
Q

What is nuclear pores?

A

Gaps in the nuclear envelope controlling exit and entry into nucleus

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20
Q

What is nuclear envelope

A

Membrane surrounding nucleus

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21
Q

What is DNA

A

Deoxyribonucleic acid - encodes our phenotype

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22
Q

What is a histone

A

Protein which DNA binds to

23
Q

What is nucleosome

A

Structure formed from DNA wrapped twice around 8 histone proteins

24
Q

What is chromatin

A

A length of nucleosomes (structures with DNA wrapped around 8 histone proteins)

25
Q

What is chromosome

A

Fully condensed form of DNA where chromatin condenses further to chromatin fiber which condenses into loops then stacking to form chromosomes

26
Q

What are genes

A

A length of DNA that codes for a phenotype/function

27
Q

What is diploid organism

A

Organisms with two sets of chromosomes

28
Q

What determines accessibility of DNA in the nucleus

A

Extent of coiling - more coiling reduces accessibiltiy

29
Q

What are ribosomes

A

Two subunits, small and large made up of rRNA in complex with many proteins

Assembled in nucleolus and exited through nuclear pores

30
Q

What do ribosomes do

A

Protein synthesis, they are found in two places

free in the cytoplasm- making cytosol proteins
attached to RER- making endomembrane proteins

31
Q

What is ER

A

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

32
Q

What are the 2 types of ER

A

Rough and smooth

33
Q

What is rough ER

A

Extension of nuclear membrane dotted with attached ribosomes

34
Q

What is rough ER function

A

Ribosomes produce proteins which enter the lumen of ER for folding. Then rough ER membrane surrounds protein forming transport vesicles destined for golgi

Production of secreted proteins, membrane proteins, organelle proteins

35
Q

What is smooth ER

A

Extension of rough ER with no ribosomes

36
Q

What is smooth ER function

A

Lipid synthesis
Storage of cell-specific proteins

Function of smooth ER varies a lot from cell to cell

37
Q

What is golgi appartus

A

A complex made up of 3-20 flattened membranous sacs called cisternae stacked on top of one another

38
Q

What is golgi apparatus function

A

Modify sort package and transport proteins from rough ER using enzymes present in each cisternae

Formation of vesicles (3types):
secretory vesicles
membrane vesicles
transport vesicles

39
Q

What are lysosomes

A

Vesicles produced by golgi apparatus containing digestive enzymes

Highly acidic due to constant pumping of H+ ions via membrane proteins

40
Q

What is lysosome function

A

Digestion of:
substances entering cell
cell components
entire cells

41
Q

What are mitochondria

A

Membrane bound organelles that generate ATP through cellular respiration

Made of inner and outer membrane where the inner membrane folds to form cristae. Inside of mitochondria is filled with fluid called mitochondrial matrix

Carry own genome

Number of mitochondria depend on ATP needs

42
Q

How does mitochondria produce ATP

A

ATP -> ATP + phosphate

Energy is released in this process

43
Q

What is cytoskeleton

A

Structural support system of cell - determines size shape integrity of cell

44
Q

What is cytoskeleton function

A

Act as scaffolding across cell

Involved in intracellular transportation and cell movement

45
Q

What are the 3 types of fibers that make up cytoskeleton

A

Microfilaments
Intermediate filaments
Microtubules

46
Q

What is the diameter of microfilaments

A

7 nm

47
Q

What are microfilaments and where are they found

A

Comprised of actin molecules assembled in two long chains, twisted around each other

Found around the periphery and lining the interior of cell

48
Q

What is microfilament function

A

Bear tension and weight by anchoring cytoskeleton to plasma membrane proteins
Promote amoeboid motility if required (movement of cell)

49
Q

What is the diameter of intermediate filaments

A

8-12nm

50
Q

What are intermediate filaments and where are they found

A

Comprised of diverse range of different materials and found in cytoplasm

51
Q

What is intermediate filament function

A

Bear tension and weight throughout the cell

Act as scaffold for cellular organelles

52
Q

What is the diameter of microtubules

A

A tubular structure, 25nm in diameter with a central lumen of 15nm

53
Q

What is microtubule

A

Comprised of tubulin dimers coiled to form a tube

Extends from centriole into cytoplasm/nucleus

54
Q

What are functions of microtubules

A

Support cell shape and size
Guide for movement of organelles
Chromosome organisation - cell division
Support and movement of cillia and flagella