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biology exam - 1 & 2 > CH4 cell growth, death and differentiation > Flashcards

CH4 cell growth, death and differentiation Flashcards

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1
Q

what is the purpose of replication in eukaryotes?

A
  • reproduction
  • growth and development
  • maintainance and repair
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2
Q

what is the purpose of replication in prokaryotes?

A
  • reproduction
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3
Q

what is binary fission?

A

binary fission is when prokaryotes reproduce rapidly and produce two genetically identical copies of a cell.
- it is a type of asexual reproduction

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4
Q

what are the steps of binary fission?

A
  • DNA Replication- the circular chromosome uncoils and replicates
  • Cell elongation - the duplicated chromosome and plasmids migrate to opposite ends
  • Cytokenesis- a septum, new cell wall and membrane, form down the middle resulting in the creation of two new daughter cells.
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5
Q

What is Apoptosis?

A

the natural and controlled death of cells within our body which plays an important role in our development and day- to - day lives

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6
Q

what are the two pathways of Apoptosis?

A
  • Mitochondrial pathway
  • Death receptor pathway
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7
Q

what is the mitochondrial pathway?

A
  • internal components of the cell (e.g. DNA) are damaged, mitochondria will detect this damage and release Cytochrom c into the cytosol
  • Cytochrome c will bid with the cystolic proteins to form an apoptosome, which activates caspase enzymes, imitating apoptosis.
  • Also known as the intrinsic pathway
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8
Q

what is cytochrome c?

A

a protein embedded in the inner mitochondrial membrane

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9
Q

what are caspase enzymes?

A

catalysts
that cleave specific intracellular
proteins during apoptosis

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10
Q

what is the death receptor pathway?

A
  • the pathway of apoptosis which is initiated by death receptor proteins on the surface of cells recepting extracellular death signalling molecules.
     - when the molecules bind to a death receptor surface protein, caspase enzymes are activated.
     - Also known as the extrinsic pathway
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11
Q

what are the stages of apoptosis and what happens at each stage?

A

caspase activation - activated by either the mitochondrial or death receptor pathway
digestion of cell contents - caspases cleave proteins and digest organelles
cell shrinkage- cell shrinks due to digestion
blebbing and breakage - organelles and cytoskeleton are digested, apoptopic bodies detatch from the cell.

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12
Q

what is necrosis?

A

Necrosis is the unregulated death of cells initiated by
significant damage which causes the cell to swell, burst, and release cell contents into the surrounding
environment. This may lead to inflammation and damage in nearby cells and tissues.

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13
Q

purposes of apoptosis?

A
  • cells which are damaged or effected must be eliminated
  • during fetal development, apoptosis sculpts the body from tissues.
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14
Q

phagocytosis

A
  • after apoptosis, phagocytes engulf and digest the free- floating apoptopic bodies by phagocytosis
  • lysosomes in the phagoctyes cell digest the contents of the food vacuole which eliminates the contents of the cell which dies from apoptosis.
  • phagocytosis is endocytosis of solid
    material or food particles
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15
Q

how can cells die?

A

through apoptosis or necrosis

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16
Q

what can happen if apopotsis fails?

A

cancers can form

17
Q

what is a stem cell?

A

a cell that is undifferentiated yet is capable of further differentiating into various different cell types.

18
Q

what are the properties of a stem cell?

A

self renewal- stem cells can replicate into both a differentiated and undifferentiated cell

differentiation- stem cells are undifferentiated cells which can gove rise to differentiated cells with specialised functions

19
Q

what are the 3 main types of potency?

A

totipotent
pluripotent
multipotent

20
Q

what is a totipotent cell?

A

a totipotent cell can differentiate into either an embryonic or extraembryonic stem cell (e.g placenta)

21
Q

what is a pluripotent cell?

A

pluripotent cells can differentiate into any type of embryonic stem cell of one of the three germ layers.

22
Q

what is a multipotent cell?

A

stem cells that can differentiate into a limited number of specialised cell types belonging to a specific tissue or organ
- endoderm
- mesoderm
- ectoderm
(e.g. adult stem cells)

23
Q

what is a blastocyst?

A

a group of cells that forms early into pregnancy (5-6 days) and these cells are pluripotent meaning it can differentiate into any embryonic cell.

24
Q

what is interphase?

A

G1- growth and the synthesis of organelles and proteins necessary for DNA replication
S PHASE- DNA replication
G2- cell continues to grow in preparation of mitosis

25
Q

what happens in G1?

A

the cell grows by
1. increasing the volume of its cytosol
2. synthesising proteins for DNA replication
3. replicating its organelles

26
Q

what happens in S phase?

A

the cell replicates its DNA turning one chromosome into two identical sister chromatids yet is still referred to as a single chromasome. I -> X - diagram

Chromatids- one half of a double-stranded chromosome

27
Q

what happens in G2?

A

cells continue to grow and prepare itself for mitosis by
1. increasing the volume of cytosol
2. synthesising proteins in preparation for mitosis

28
Q

what is mitosis?

A

it is the separation of the newly replicated chromosomes into new nuclei.

the stages are:
1. prophase
2. metaphase
3. anaphase
4. telophase

29
Q

what happens in prophase?

A
  • centrioles separate to opposite ends and spindle fibres appear
  • chromosomes condenseand begin to align
  • breakdown of nuclear membrane
30
Q

what happens in metaphase?

A
  • spindle fibres attatch to chromosomes by the kinetochore using fibres to attatch to the spindle fibres.
  • chromosomes align across the equator of the cell
31
Q

what happens in anaphase?

A

— centromeres divide
- contraction of spindle fibres
- sister chromatids are dragged to opposite poles of the cell by the kinetochore.
- after the chromatids are split we now have separate chromosomes

32
Q

what happens in telophase?

A
  • chromosomes decondense and becoming curled up and thinner.
  • nuclear membrane reforms as chromosmes continue to decondense.
  • spindle fibres dissapear
  • contractile ring of fibres forms and creates a cleavage furrow in the cell membrane.
33
Q

what happens in cytokenesis?

A
  • cytoplasm divides
  • parent cell becomes two daughter cells with identical genetic information.
  • nucleolus has fully reappeared and chromosomes have fully condensed.
  • membrane vesicles move to the constriction of the contractile ring and fuse the membrane, creating two separate cells.

biology exam - 1 & 2 (9 decks)

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