🩢 3.2.2 All Cells Arrise From Other Cells Flashcards

(25 cards)

1
Q

Can all multicellular organisms divide?

A

No, within multicellular organisms, not all cells retain the ability to divide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do eukaryotic cells that do determine the ability to divide show?

A

They show a cell cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When does DNA replication occur?

A

It occurs during interphase of the cell cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the purpose of mitosis?

A
  • For eukaryotes to grow
  • For eukaryotes to replace damaged cells
  • For eukaryotes to asexually reproduce
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define mitosis

A

The process of cell replication in eukaryotes resulting into genetically identical daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define chromosome

A

Double or single structure composed of linear DNA wrapped around histone proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define chromatid

A

Identical sister chromatids make up the double structure of a chromosome when joined together with a centromere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define centromere

A

These join the identical sister chromatids together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define centriole

A

Organelles which produce spindle fibres in order to make the chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define spindle fibres

A

Proteinous structures which connect the centrioles to the centromeres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define cytokinesis

A

Division of the cytoplasm during telophase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the first step of mitosis called and what happens during it ?

A

It is called prophase.
- the chromosomes shorten, thicken and therefore condense thus becoming more visible
- each chromosome can be seen to consist of two identical, sister chromatids joined via a centromere
- the nuclear membrane breaks down and centrioles move towards either pole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the second step of mitosis called and what happens during it?

A

It is called metaphase.
- each chromosome is joined, via its centromere, by spindle fibres to the centrioles
- the chromosomes are lined up in single file along the equator of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the third step of mitosis called and what happens during this stage ?

A

This step is called anaphase.
- the spindle fibres contract and each of the identical, sister chromatids are pulled to the opposite pole
- the centromeres divide
- the chromatids form a characteristic β€˜ V β€˜ shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the fourth step of mitosis called and what happens during this stage?

A

It is called telophase.
- the identical sister chromatids now start to be referred to as chromosomes again
- the chromosomes start to lengthen again
- the cytoplasm divides (cytokinesis) and the cell membrane of the two identical, daughter cells (clones) reforms
- the nuclear membrane reforms in the two new cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the product of mitosis?

A

Two daughter cells, each with the identical copies of DNA produced by the parent cell during DNA replication

17
Q

What kind of process is mitosis?

A

It is a controlled process

18
Q

What can uncontrolled cell division lead to ?

A

The formation of tumours of cancer

19
Q

What do many cancer treatments focus on doing ?

A

Many cancer treatments are directed at controlling the rate of cell division

20
Q

Which organisms don’t undergo cell division and why?

A

Viruses don’t undergo cell division as they are non living. Instead, after the injection of their nucleic acid, the infected host cell replicates the virus particles

21
Q

Which organisms do binary fission?

A

Prokaryotes - specifically bacteria cells

22
Q

Give the method for binary fission

A

1- circular DNA replicates
2- plasmids replicate many times unpredictably
3- semi conservative replication occurs
4- circular DNA moves to either pole
5- plasmids move to poles
6- the cell elongates
7- cytoplasm divides
8- cell wall reforms
9- plasmids may divide unequally so they are not referred to as clones or identical cells

23
Q

Describe the steps of how to prepare a temporary mount and estimate the size of a cell

A
  • cut the specimen thinly to allow light to penetrate the single layer of cells
  • a drop of water can assist this
  • when adding the specimen to the slide, add stain to make organelles visible and supply contrast
  • add the coverslip to the specimen, lowering it with a mounted needle, and press firmly down to ensure the specimen is one cell thick and so any air bubbles are removed
  • the microscope needs to be calibrated in order for cells to be measured
  • a random number generator can be used to choose the cells to measure in order to not be biased
  • many cells need to be measured in order to make the sample representative
    (The above two points are done to increase reliability)
  • a mean size of cells can be calculated
24
Q

When measuring an organism on the stage what do you use ?

A

An eye piece graticule

25
How to use the eye piece graticule ?
- the eye piece graticule needs calibrating at each new magnification - the EPG is lined up against the stage micrometre so that each EPV can be assigned a length - once this is achieved the stage micrometre can be discarded and the specimen can be measured