Cell Division Flashcards

1
Q

What do all cells develop from?

A

Pre-existing cells

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2
Q

What are the steps to form a new cell and how many are there?

A

3 steps to form a new cell

  • Produce materials it will need
  • Grow larger
  • Reproduce to form a new cell
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3
Q

What are chromosomes?

A

Structures in Nucleus, made of DNA and Protein

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4
Q

What do we call chromosomes when they are not dividing?

A

Chromatin forms a number of clearly distinguishable chromosomes

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5
Q

How many chromosomes does each species have?

A

Each species has a definite no. of Chromosomes, Humans = 46 chromosomes

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6
Q

How many genes does each chromosomes have?

A

Each chromosomes has 1000s of genes

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7
Q

Draw and label a pair of homologous chromosomes.

A

.

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8
Q

What is a Haploid?

A

A Haploid cell has one set of chromosomes, i.e. has only one set of each type of chromosomes in the nucleus.

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9
Q

What is Haploid symbolised by?

A

the letter n

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10
Q

What is the number of chromosomes in the Haploid cell given as?

A

n=23

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11
Q

What type of cell are humans eggs and sperm?

A

haploid n=23

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12
Q

What is a diploid?

A

A Diploid has two sets of chromosomes, i.e. It has two of each type of chromosome in the nucleus

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13
Q

How are chromosomes organised in a diploid cell?

A

Chromosomes are in pairs in diploid cell, called homologous pairs.

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14
Q

How is a diploid symbolised as and what is the total no. of chromosomes in a diploid cell given as?

A

Diploid is symbolised as 2n and total no. of chromosomes in cell is given as 2n = 46

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15
Q

Where do the chromosomes come from in a diploid cell?

A

In diploid cells, 1 chromosome from the homologous pair comes from the mother and the other comes from the father

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16
Q

What is the cell cycle?

A

Describes the life of a cell. It includes the period between division when the cell is not dividing, called Interphase.

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17
Q

What is the period when a cell divides called?

A

Mitosis

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18
Q

What is interphase?

A

The period between division when the cell is not dividing

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19
Q

How long is interphase?

A

Longest phase in cell cycle = 90% of a cells life is in interphase

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20
Q

What are chromosomes called in interphase? What is one difference between them and chromosomes?

A

chromatin

not elongated

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21
Q

What are cells like in interphase, what do they do?

A

Cell very active in Interphase, produces new mitochondria, chloroplasts etc. and chemicals needed for growth

22
Q

What is mitosis?

A

Mitosis is a form of nuclear division in which one nucleus divides to form two nuclei, each containing identicals sets of chromosomes.

23
Q

What are the two new cells called formed by mitosis? What is one feature of them?

A

Two new cells called daughter cells and they are IDENTICAL to each other

24
Q

What are the functions of mitosis in Unicellular Organisms?

A

Method of reproduction for Amoeba Reproduction that does not involve the joining of 2 cells is called asexual reproduction.

25
Q

What are the functions of mitosis in multicellular organisms?

A

Produces new cells, not new individuals

Responsible for growth and renewal and repair of cells

26
Q

what is important the body does to the rate of cell division?

A

Rate of cell division (mitosis) is carefully controlled

27
Q

What sometimes happens to a cell or group of cells in mitosis?

A

Sometimes a cell or group of cells lose the ability to control the rate of cell division

28
Q

What happens when a cell or group of cells loves the ability to control the rate of cell division?

A

They form a mass of cells called a tumour which can be benign or malignant

29
Q

What does benign mean?

A

Benign means kind, they are not life threatening and do not invade other tissues. E.g. warts, skin tags. Cells stop dividing after some time.

30
Q

What is cancer?

A

Cancer is a group of disorders in which certain cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place.

31
Q

What are malignant tumours?

A

Uncontrolled multiplication of abnormal cells
Malignant tumours (cancers) invade other cells and move around the body.
Movement of these cells called Metastasis.
Cancer cells divide indefinitely

32
Q

What is the movement of cells invaded by malignant cancers called?

A

metastasis

33
Q

What are the causes of cancer?

A

Caused when normal genes are altered to form cancer-causing genes called oncogenes.
Brought about by cancer causing agents called carcinogens e.g. cigarette smoke, asbestos fibres, ultraviolet radiation and some viruses

34
Q

How can most cancers be cured?

A

Most cancers can be cured with radiation (burn out cancer), chemotheraphy (chemicals sllow down mitosis and surgery

35
Q

What is meiosis?

A

Meiosis is a form of nuclear division in which the daughter nuclei contain half the chromosome number of the parent nucleus.

36
Q

How many chromosomes do human cells have?

A

46

37
Q

Where does meiosis occur in humans and what does it do?

A

Meiosis occurs in the ovaries and testes to produce gametes called eggs and sperm so there are 23 chromosomes in each egg and sperm.

38
Q

How many chromosomes are there in each egg and sperm?

A

There are 23 chromosomes in each egg and sperm.

39
Q

How many functions of meisosis are in multicellular organisms?

A

2

40
Q

What does meiosis allow?

A

Allows sexual reproduction without increasing the number of chromosomes in the offspring. Allows new combinations of genes.

41
Q

What is the sentence to help you remember the 4 stages of mitosis?

A

I Party Monday And Tuesday

interface is not really a stage of mitosis [I]

42
Q

Draw a diagram of prophase

A

pg. 162 - 14.23

43
Q

How many stages of mitosis are there?

A

4 in total

44
Q

What happens in the prophase stage?

A

At end of Interphase, Chromosomes contract and become visible. Each chromosome appears as a duplicated strand. Fibres appear in cytoplasm. Nuclear membrane starts to break down.

45
Q

What happens at the end of Interphase?

A

The prophase stage

46
Q

What happens in metaphase?

A

Nuclear membrane broken down
Chromosomes thicken even more
Chromosomes line up across the centre of cell
Fibres attach to chromosomes
Each chromosome has 2 fibres attached, 1 from each side of the all.

47
Q

Draw a diagram of metaphase

A

.

48
Q

What happens in anaphase?

A

Fibres contract, chromosomes pulled apart
Each strand is pulled to opposite end of cell
Hence, identical set of genes pulled to each end of the cell.

49
Q

Draw a diagram of anaphase

A

.

50
Q

What happens in telophase?

A

Nuclear membrane forms around each of the 2 sets of chromosomes.
Chromosomes elongate within each nucleus
Mitosis is complete. Once complete, original cells divide to form 2 cells.

51
Q

Draw a diagram of telophase

A

.