2.6 Cell divison, cell diversity and cell diffentiation Flashcards Preview

Biology - Module 2 > 2.6 Cell divison, cell diversity and cell diffentiation > Flashcards

Flashcards in 2.6 Cell divison, cell diversity and cell diffentiation Deck (32)
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1
Q

What is the definition of tissue?

A

A group of similar cells carrying out a specific function.

2
Q

What is the definition of an organ?

A

A collection of tissues that work together to carry out a specific function.

3
Q

What are the different tissue types in a animals?

A
  • epithlial (skin, gut/airways lining)
  • connective (bone, ligament cartilage)
  • muscle (smooth, cardiac, skeletal)
  • nervous (neurons)
4
Q

What are the different tissue types in plants?

A
  • epidermal (protective covering over leaves, stems and roots)
  • vascular (xylem and phloem)
  • meristematic (stem cells, found at root and shoot tips)
5
Q

What are the different phases in the cell cycle?

A

1) G1 (growth one)
2) S
3) G2 (growth two)
4) M (mitosis/not interphase)

6
Q

What happens in G1?

A
  • cells grow and increase in size
  • transcription of genes to make RNA
  • organelles duplicate
  • biosynthesis is enzymes needed to make DNA
  • p53 (tumour suppressor) gene helps control this phase
7
Q

What happens at the G1 checkpoint?

A

Control mechanisms ensure that the cell is ready to enter s-phase.

This is the point of no return, if it does not pass this check point it will enter G-0

Once passed, mitosis will occur.

8
Q

What is the G-0 phase?

A

A phase triggers during G1 checkpoint, if it does not pass.

In this phase, it can either undergo apoptosis, differentiation or senescence.

Some cells which have a long cell life may stay in this stage for a very long time.

9
Q

What happens in the S-phase?

A

This is when DNA replicates; this phase is rapid as it when he DNA base pairs are exposed, they are more susceptible to mutagenic agents, hence reduces the chances of mutations.

Housekeeping genes are replicated first, and then the inactive genes are replicated last.

10
Q

What happens in G2?

A

The cell continues to grow, mitochondria and chloroplast also begin to be produced.

11
Q

What is the name of the protein which regulates checkpoints in the cell cycle?

A

Cyclin

12
Q

What are cyclin dependant kinases?

A

Enzymes which require a cyclin to work, and are used to active the next stage of the cell cycle.
So without cyclin, they will not be able to pass into the next stage so they act as a means to stop the cell cycle and prevent any cancerous cells from dividing.

13
Q

How does P53 suppress tumours?

A

P53 is an enzyme which finds and binds to damaged DNA, inhibiting the cell cycle.
It then produces a CDK (cyclin dependant kinase)inhibiter which inhibits the CDK from activiting its substrate and passing the checkpoint.

14
Q

How do enzymes lower the activation energy required?

A

IN synthesis reactions, enzymes reduce the repulsion between the molecules, reduciong the required energy.

In break down reactions, enzymes add strain on the bonds, allowing them to be broke easier.

15
Q

What is meant by saturtion in terms of enzymes?

A

It means that all active sites of all the enzymes are in use, so the rate of reaction cannot increase past this point, unless more enzymes are added.

16
Q

What is chromatin?

A

DNA that has not yet been coiled

17
Q

WHat is a kinetochore?

A

Proteins which attach the chromosomes to the spindle fibres during mitosis.

18
Q

How are chromosomes moved during mitosis?

A

Motor proteins

19
Q

What are centromeres?

A

The middle of a chromosome which joins the two chromotids.

20
Q

What is an actin ring?

A

A ring of protein around an animal cell which, during cytokinesis, contracts to split the cell in two.

21
Q

What is the cleavage furrow?

A

An indentation which appears when the actin conctractile ring begins to contract.

22
Q

How do plant cells split in two during mitosis?

A

A cellulose wall develops down the middle.

23
Q

How do you calculate mitotic index?

A

(Number of cells in mitosis/total number of cells) x 100

24
Q

What is asymetric division?

A

A type of cell division which stem cells use, which produces two non-genteically identical cells.

25
Q

What four uses are there for stem cells?

A
  • Bone marrow transplant (restore patients blood system after treatment such as wiping the immune system)
  • Drug research (on specialist tissues)
  • treatment for genetic diseases
  • regenerative medecine (to replace damaged specialised cells)
26
Q

What are homologous chromosomes?

A

Matching chromosomes that contain the same genes, at the same loci. They may contain different alleles for some of the genes.

27
Q

How many chromosomes does meiosis make in a cell?

A

Half the number of the parent

In humans, this means haploid, which is 23 chromosomes.

28
Q

What events in prophase 1 of meiosis increase genetic variation?

A

Crossing over of non-sister chromatids

29
Q

What are sister chromatids?

A

Two identical chromosomes which form an homologous pair.

30
Q

What occurs in metaphase 1 of meiosis that increases genetic variation?

A

Independent assortment

This is when the homologous pairs are arranged randomly along the equator.

31
Q

What is different between meiosis 1 and meiosis 2?`

A
  • M1 produces the same number of chromosomes as M2, but each chromosome contains two chromatids
  • M2 works to separate the chromosomes so that in anaphase 2, the two chromatids are pulled apart
  • M2 produces 4 cells
32
Q

How does meiosis produce genetic variation?

A
  • Crossing over during prophase 1 shuffles alleles
  • Independant assortment of chromosomes in metaphase 2
  • Independent assortment of chromatids in metaphase 2
  • Haploid gametes are produced which undergo random fusion with gametes derived from another organism during fertilisation