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BIOL1040 > Lesson 3 - Nuclear Cell Biology > Flashcards

Lesson 3 - Nuclear Cell Biology Flashcards

1
Q

Exception to a human cell that does not contain a nucleus

A

Erythrocyte

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2
Q

What is the nucleus separated from the cytoplasm by

A

The nuclear envelope/membrane

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3
Q

What does the nuclear membrane have that allows large molecules to synthesise in the nucleus to pass into the cytoplasm?

A

Pores which allow large molecules (e.g. peptides that form together to create a protein) to synthesise in the nucleus and then to pass into the cytoplasm

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4
Q

Is the nuclear membrane phospholipid?

A

Yes

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5
Q

Where is the nucleus in leukocytes?

A

Central part of the cell

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6
Q

Where is the nucleus in tall columnar cells?

A

Basal (base) of the cell

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7
Q

Where is the nucleus in skeletal muscle cells?

A

Peripheral (sides)

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8
Q

Why does the nucleus stain intensely with basic dyes?

A

Because it has a combination of euchromatin and heterochromatin

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9
Q

What is euchromatin?

A

Chromatin that is the same or very similar. Euchromatin is abundant in active nuclei e.g. plasma cells

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10
Q

What is heterochromatin?

A

Chromatin that is different. It is abundant in inactive cells e.g. nuclei of small lymphocytes

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11
Q

Genes determine what?

A

Organism characteristics

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12
Q

What are the 4 components of DNA

A

Cytosine, Guanine, Adenine, Thiamine

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13
Q

Chromosomes are

A

Discrete collections of genes and nuclear proteins

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14
Q

What is a phenotype?

A

Genes that determine what people are going to look like

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15
Q

What is a genotype?

A

Genes that determine someone’s internal framework and structure

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16
Q

2 membranes of the nucleus

A

Inner and outer nuclear membrane

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17
Q

Outer membrane becomes … with an organelle

A

Continuous

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18
Q

What does it mean when the outer membrane becomes continuous with an organelle?

A

When peptides go out of the nucleus to assemble to form a protein, they go onto the RER. The lumen of the RER is directly connected to the space between the two nuclear membrane. The RER then synthesises the protein by a ribosome and then carries it in a vesicle frm the RER to cis face of golgi apparatus

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19
Q

Inner membrane has…

A

Anchors that holds chromatin in place

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20
Q

What is chromatin?

A

Is like a chip that sits inside a device
Located in the nucleus
Is a mass of genetic material that is composed of DNA and protein that condenses into chromosomes during eukaryotic cell division

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21
Q

Purpose of the nuclear matrix?

A

Ensures that chromatin is safe and provides medium that raw material can enter the nucleus to generate whatever

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22
Q

Difference between nucleus and nucleolus

A

Nucleolus is a dense mass in the centre of the nucleus.

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23
Q

When is the nucleolus barely visible

A

In the resting or active stage

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24
Q

When does the nucleolus become more visible

A

During interphase, disappearing during metaphase and reappearing during telophase

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25
Q

In mitosis, the number of chromosomes must remain the…

A

Same

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26
Q

What is the diploid number

A

46

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27
Q

When a cell divides by a mitotic process, a parent will give rise to 2 daughter cells with how many chromosomes?

A

46 chromosomes each but are smaller in size

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28
Q

During mitosis, what is generated

A

Mitotic spindle

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29
Q

What is mitotic spindle?

A

It is located at the spindle poles. It is a process where kinetochore microtubules attach to chromosomes in the middle of the cell and travel to the spindle pole.

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30
Q

What is the role of kinetochore microtubules

A

To transport the chromosomes from the middle of a cell to the spindle poles

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31
Q

What is the role of aster and interpolar microtubules

A

To hold everything in place

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32
Q

Where do microtubules radiate to?

A

Away from each spindle towards the chromosome assembled on the metaphase plate

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33
Q

Do the aster and interpolar microtubules attach to chromosomes?

A

No - only kinetochore microtubules do

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34
Q

How many chromosomes do the daughter cells have in meiosis

A

23 (haploid number)

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35
Q

What does meiosis produce

A

Haploid sex cells or gametes

36
Q

Where does meiosis occur

A

The gonadal cells

37
Q

Why do the daughter cells in meiosis have a haploid number?

A

Because when the sperm fertilises the egg, they will combine to form 46 chromosomes

38
Q

What phases are known as interphasse?

A

Period between mitotic division (G1, S and G2)

39
Q

What is the M phase in the cell cycle?

A

Where nuclear division (mitosis) is followed by cell division (cytokinesis)

40
Q

What is G1 phase

A

Metabolic changes (all the organelles like mitochondria, golgi apparatus etc.) prepare the cell for division. It is responsible for making sure a copy of organelles go into the 2 daughter cells

41
Q

What is S phase

A

DNA synthesis - replicates genetic material (in order for division to occur to result in 46 chromosomes each)

42
Q

What is G2 phase

A

Metabolic changes all assemble the cytoplasmic materials (basically a double check to check for errors in the duplicated chromosome)

43
Q

2 major components of the extracellular matrix

A

Fibres and Matrix

44
Q

Most common fibers

A

Collagen

45
Q

What is the benefit of collagen being stringy and tough?

A

To allow for organs to have specific shapes and structure e.g. tendons and ligaments have a lot of collagen because they need to be strong.

46
Q

Why is it hard to tear a ligament but easy to tear a blood vessel?

A

Because ligaments have high collagen whereas blood vessels dont

47
Q

What is the matrix around a cell made up of?

A

Proteoglycans (protein and glucose)

48
Q

What does connective tissue consist of?

A

Cells, fibres, extracellular matrix

49
Q

What is the role of connective tissue?

A

It covers the brain, lungs and provides attachment sites for muscles

50
Q

4 basic types of connective tissue

A
  1. Epithelial - skin
  2. Connective tissue of cells - collagen fibres
  3. Muscular tissue
  4. Nervous tissue
51
Q

3 types of fibres:

A
  1. Reticular fibres: Have protein called reticulin. Has criss-cross protein arrangement like a band-aid
  2. Elastic fibres: Located where organs need to be stretched or deflated e.g. lungs
  3. Fibronectin: Provides strength and stability to cells. Links cells to other EC matrix components e.g. collagen
52
Q

4 important functions of the basement membrane

A
  1. Attachment of epithelial cells
  2. Barrier preventing microorganisms from entering the organisms in a domain
  3. Loss of cell fluids from the body
  4. Selective filtration
53
Q

Why does skin have a thicker basement membrane than other locations?

A

So that bacteria from the external environment doesn’t go in to the body

54
Q

4 constituents of the basement membrane

A
  1. Laminin
  2. Type 4 collagen
  3. Heparan sulphate
  4. Fibronectin
55
Q

2 major fluid compartments in the body:

A

Intracellular (2/3 of total water)
Extracellular (1/3 of total water)

56
Q

What is extracellular fluid comprised of?

A

Interstitial fluid that is between cells and plasma that is between blood cells.

57
Q

Is diffusion a non-energy consuming process or energy consuming?

A

Non-energy

58
Q

Osmosis

A

Where fluid of a lower solute concentration moves from one side of a semi-permeable membrane to another of a higher solute concentration

59
Q

Most membranes are permeable or semi-permeable

A

semi-permeable

60
Q

3 factors needed for diffusion to occur?

A
  1. Bigger surface area, quicker diffusion occurs
  2. Concentration gradient needs to exist (difference in concentration between 2 sides of a membrane where particles from higher concentration travel to lower concentration during passive transport)
  3. Thickness of membrane is important too. If membrane is thin, diffusion is quick
61
Q

Facilitated diffusion occurs through what proteins

A

Either transmembrane proteins (gated channels) or carrier proteins (in the membrane)

62
Q

How does a molecule move into a cell?

A

Transmembrane protein is activated by a chemical messenger which then opens the channel and allows the molecule to come in.

63
Q

2 types of active transport

A
  1. Primary active: involves direct expenditure of energy in the form of ATP to transport ion in and out of cell e.g. pump that pumps sodium out and potassium in
  2. Secondary active: The concentration gradient of one molecule provides the energy for the transport of another molecule against the latter’s concentration gradient.
64
Q

3 types of molecule transport strategies

A
  1. Uniporters: Membrane proteins that recognise 1 specific molecule in or out such as fructose.
  2. Symporters: when 2 molecules are moving from the inside to the outside. e.g. hydrogen being pumped out and sucrose joins in. Utilises concentration gradient
  3. Antiporters: While 1 molecule comes in, another comes out using concentration gradient.
65
Q

When does osmosis occur?

A

When osmotic pressure is present - allows fluid of higher concentration to area of lower concentration

66
Q

Ion channels show…

A

high selectivity by allowing only specific ions to pass down their concentration gradient

67
Q

How are ligand-gated channels opened?

A

Binding of a ligand (molecule or ion that binds to a central atom for cellular signalling and regulation) specific for that channel e.g. acetylcholine binding to nicotinic receptors. Primarily located on dendrites or cell body.

68
Q

How are voltage gated channels opened?

A

In response to a change in membrane voltage. Common on nervous system membranes.

69
Q

How are gap junction channels formed?

A

Alignment of hemichannels called connexons, connecting the cytoplasm of the cells to allow passage of ions and small molecules between them. Can be electroneutral.

70
Q

What is the job of gap junction channels?

A

To act as troughs e.g. salivary gland - mass flux of sodium and water via these channels he

71
Q

3 vesicular membrane transport mechanisms

A
  1. Exocytosis
  2. Endocytosis
  3. Transcytosis
72
Q

What is exocytosis

A

Fusion of vesicles to the cell membrane for extrusion (where cells export large particles or organelles through its cell membrane to the outside of substances)

73
Q

What is endocytosis

A

Process by which a substance or particle outside the cell is engulfed by the cell membrane, forming a vesicle.

74
Q

2 types of endocytosis

A
  1. Phagocytosis: engulfing large particles
  2. Pinocytosis: engulfing fluid (cell drinking) and small particles associated with the engulfed fluid
75
Q

What is transcytosis

A

Moving things around cells - occurs in capillary endothelial cells and intestinal epithelial cells to move material across the cell via endocytosis and exocytosis.

76
Q

What does the suffix “-ASE” mean

A

that its an enzyme

77
Q

In cell signalling, what are the 3 chains that are apart of the G-protein?

A

Alpha, beta, gamma

78
Q

Process of cell signalling

A

Alpha chain from G-protein moves onto enzyme called adenylyl cyclase which helps break down ATP to cyclic AMP (cAMP) to release energy. cAMP acts as a second messenger which ends up producing certain effects - producing phosphokinase A

79
Q

How do cells signal in muscle contraction?

A

Alpha chain from G-protein moves onto phospholipase C and then activates 2 pathways: DAG and PK-C pathway. It then activates IP3 which then acts on the membrane receptors on the RER to cause calcium to come out in order for muscle contraction occur.

80
Q

What is the process of cell signalling controlled by?

A

GPCR (g-protein coupled receptor)

81
Q

3 Steps of cell signalling

A
  1. Reception (signalling molecule attaches onto receptor)
  2. Transduction (3 relay molecules are transported in a signal transduction pathway into nucleus)
  3. Response: activation of cellular response e.g. activation of glycogen phosphorylase
82
Q

Example of primary active transport

A

Sodium out, potassium in for ATP

83
Q

Example of passive transport

A

Sodium channel, Potassium channel, glucose uniporter

84
Q

Example of secondary active transport

A

Ca antiporter

85
Q

What determines osmotic movement

A

It is not the concentration of molecules but is instead the total concentration of all dissolved substances (osmolarity)

BIOL1040 (6 decks)

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