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Tissue Biology > Cell Structure > Flashcards

Cell Structure Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

How could you describe the cell as a system?

A

A system of membrane bound compartments each with a unique biochemical environment

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2
Q

What does the phospholipid bilayer consist of?

A

A polar hydrophilic head and a non polar hydrophobic tail

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3
Q

What does amphipathic mean?

A

Contains a hydrophobic and hydrophilic side

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4
Q

What percentage of the phospholipid bilayer is made up of proteins?

A

Roughly 50%

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5
Q

What are the three types of proteins?

A

Intrinsic, peripheral and transmembrane

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6
Q

Why does the EM of a bilayer show it as a trilaminar layer?

A

The outer edges are electron dense due to the hydrophilic head of inner layer and lipid tails of each layer but the central is electron lucent

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7
Q

What does the nucleus contain?

A

DNA and protein called nucleoprotein

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8
Q

What percentage of the nucleus is DNA?

A

20%

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9
Q

What types of nucleoprotein are there?

A

Histone proteins and non-histone proteins such as RNA

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10
Q

The nucleus is said to be heterogeneous, why?

A

It has electron dense and electron lucent areas

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11
Q

What is the electron dense area in the nucleus?

A

Inactive coiled chromatin found in irregular clumps

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12
Q

What is the electron lucent area in the nucleus?

A

Euchromatin - DNA active in RNA synthesis

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13
Q

Cells that are involved in highly active protein synthesis are able to be distinguished by staining due to…

A

A very dense nucleoli is present

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14
Q

The ribosomes and ribosomal RNA are constructed in the

A

nucleolus

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15
Q

Once the ribosomes and ribosomal RNA have been constructed where are they transported to?

A

The cytoplasm

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16
Q

In protein synthesis, what is transcription?

A

The DNA template of a particular protein is copied to form RNA

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17
Q

mRNA has _____ spliced out. Fill the gap

A

Introns

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18
Q

The mRNA is translated into a protein at which site?

A

The ribosomes

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19
Q

What is an intron?

A

A segment of a DNA or RNA molecule which does not code for proteins and interrupts the sequence of genes

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20
Q

Describe the general structure of the rough endoplasmic reticulum

A

A system of flattened tubules covered with ribosomes

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21
Q

What is the main function of the rough endoplasmic reticulum?

A

To export proteins

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22
Q

What continues on with the rough endoplasmic reticulum?

A

The smooth ER

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23
Q

What is the difference between RER and SER?

A

The smooth endoplasmic reticulum has no ribosomes

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24
Q

What is the main function of the smooth endoplasmic reticulum?

A

Synthesis of lipids and membranes; membrane repair

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25
Q

Give a brief description of the golgi

A

Stacked membrane bound cisternae

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26
Q

What is a cisternae in the golgi?

A

refers to a flattened membrane disk that makes up the Golgi apparatus

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27
Q

What is the main function of the golgi?

A

Glycosylation of proteins and package of proteins into secretory granules

28
Q

What is the main function of the mitochondria?

A

The site of energy production by oxidative phosphorylation

29
Q

What are the four compartments of the mitochondria?

A

The outer membrane
the inner membrane
the mitochondrial matrix
the inner membrane space

30
Q

The inner membrane of the mitochondria folds to form

A

cristae

31
Q

The inner membrane space of the mitochondria contains

A

enzymes

32
Q

Lipids are found in all

A

cells

33
Q

Why can lipids not be seen during normal tissue stains?

A

The lipids are leached from the tissue during the processing

34
Q

How do we go about visualising lipids?

A

We use frozen tissues - stained with osmium tetroxide which stains the lipids black

35
Q

What is the cytoskeleton?

A

A complex network of protein filaments providing scaffolding for the cell

36
Q

Give the four main functions of the cytoskeleton

A
  1. Structure and support
  2. Intracellular compartmentalisation
  3. Cell movement
  4. Muscle contraction
37
Q

What are the three types of cytoskeleton?

A
  1. Microtubules
  2. Microfilaments/actin
  3. Intermediate filaments
38
Q

What are microtubules?

A

Hollow cylinders made up of polymers of tubulin

39
Q

What types of polymers of tubulin make up microtubules?

A

Alpha and beta tubulin

40
Q

The alpha and beta tubulin structure can be referred to as a…

A

Heterodimer

41
Q

The heterodimers of alpha and beta tubulin making up the microtubule are in the same orientation. This means there is a ____ structure

A

Polar

42
Q

Where do microtubules extend from?

A

From the centrosome

43
Q

The centrosome is an organelle that is the main place where

A

cell microtubules are organised

44
Q

Which end of the filament do microtubules grow from and where is this end found?

A

They grow from the minus end of the filament which is embedded in the centrosome

45
Q

Microtubules serve as lines of transport for example

A

for the movement of organelles

46
Q

How is movement achieved by microtubules?

A

By motor proteins which bind to specific microtubules and move in a specific direction

47
Q

Microtubules need energy in the form of ___ for ______

A

ATP and movement

48
Q

What is another name for microfilaments?

A

Actin

49
Q

Microfilaments/actin are the ____ filaments found in the cytoplasm

A

thinnest

50
Q

What is the most abundant protein in eukaryotic cells?

A

Actin

51
Q

What percentage of the total cell protein does actin make up?

A

5%

52
Q

Describe the general structure of actin/microfilaments

A

Two stranded helical polymers of G-actin protein

53
Q

Mammals have how many types of actin that are classified into how many groups?

A

6 types of actin classified into 3 groups

54
Q

What are the three groups that actin is classified into in mammals?

A

alpha actin, beta actin and y-actin

55
Q

Where is alpha actin, beta actin and y actin found?

A

a - in muscle cells/muscle differentiation - specialised to contract
b and y - non muscle cells

56
Q

Actin filaments are organised in different ways depending on?

A

The functional state of the cell

57
Q

What type of actin composition is found in non-motile cells?

A

Loose gel like network of actin

58
Q

What type of actin composition is found in motile or contractile cells?

A

Discrete structures or bundles in motile or contractile cells of actin

59
Q

Why are intermediate filaments called what they are?

A

Their average diameter is between those of actin and microtubules

60
Q

Describe the general structure of intermediate filaments

A

Elongated rope like fibrous molecules

61
Q

From where to where do intermediate filaments form their extensive network?

A

Around nucleus and out to cell periphery; span cytoplasm from one cell-cell junction to another

62
Q

What are the three classes that intermediate filaments fall into?

A

Keratin filaments, vimentin and vimentin related filaments and neurofilaments

63
Q

What is the main function of intermediate filaments?

A

Providing mechanical stability to animal cells

64
Q

Give an example of a disease caused by a mutation in the keratin gene in an intermediate filament

A

Epidermolysis bullosa simplex

65
Q

How does epidermolysis bullosa occur?

A

Defective keratin assembles with normal keratins and disrupts the keratin filament network in basal cells

66
Q

How do blisters form in patients with epidermolysis bullosa?

A

Loss of cohesion between basal epithelial cells and underlying basement membrane , blister formation and fluid loss

Tissue Biology (16 decks)

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