Topic 5: Mitotic Cell Cycle

Question 1

Anaphase

Answer 1

The sister chromatids separate at their centromere and the spindle fibres shorten. Each chromatid of the homologous pair is pulled to opposite poles of the cell.

Question 2

Centriole

Answer 2

One of two small, cylindrical structures made from microtubules, found just outside the nucleus in animal cells, in a region known as the centrosome; they are also found at the bases of cilia and flagella.

Question 3

Centromere

Answer 3

A region at which the sister chromatids are held together.

Question 4

Chromatid

Answer 4

One of two identical parts of a chromosome, held together by a centromere, formed during interphase by the replication of the DNA strand.

Question 5

Chromatin

Answer 5

The loosely coiled form of chromosomes during interphase of the cell cycle; chromatin is made of DNA and proteins and is visible as loosely distributed patches or fibres within the nucleus when when stained.

Question 6

Chromosome

Answer 6

A structure made of DNA and histone, found in the nucleus of a eukaryotic cell; the term bacterial chromosome is now commonly used for the circular strand of DNA present in a prokaryotic cell.

Question 7

Contractile Fibres

Answer 7

This is what the spindle is made from. The fibres are made of proteins called microtubules. It is the contraction of the overlapping fibres of microtubules which causes the movement of the chromatids.

Question 8

Cytokinesis

Answer 8

The division of cytoplasm to produce two genetically identical daughter cell after mitosis.

Question 9

Diploid (2n)

Answer 9

Having two complete sets of chromosomes (zygote/fertilised egg)

Question 10

Euchromatin

Answer 10

Loosely coiled chromatin in the nuclear when the cell is in interphase of the cell cycle. The genes are most active at this stage.

Question 11

Gamete

Answer 11

A haploid cell specialised for fertilisation.

Question 12

Gene

Answer 12

a length of DNA that coded for a particular protein or polypeptide.

Question 13

Haploid (n)

Answer 13

Having one complete set of chromosomes (gamete/sex cell)

Question 14

Heterochromatin

Answer 14

Tightly coiled chromatin in which chromosomes are clearly seen during nuclear division. the genes in the heterochromatin are mostly inactive.

Question 15

Histone Protein

Answer 15

These are positively charged protein molecules that DNA winds around to form nucleosomes.

Question 16

Interphase

Answer 16

The period of time between cell divisions. During interphase, the cell grows to its normal size after cell division and carries out its normal functions, synthesising many substance, especially in the process.
Interphase can be divided into 3 phases.
-G1 Phase
-S Phase
-G2 Phase

Question 17

Kinetochores

Answer 17

A protein structure found at the centromere of a chromatid to which microtubules attach during cell division.

Question 18

Metaphase

Answer 18

During Metaphase, the sister chromatids become attached to the spindle fibres by their centromere.
They are aligned along the equator of the spindle.
The centrioles reach the poles.

Question 19

Metaphase Plate

Answer 19

Chromosomes lined up in the center of the cell during Metaphase.

Question 20

Microtubule Organizing Center (MTOC)

Answer 20

Centrosome.

Question 21

Mitosis

Answer 21

The division of a nucleus into two so that the two daughter cells have exactly the same number and type of chromosomes as the parent cell.

Question 22

Mitotic Division

Answer 22

Mitosis

Question 23

Nuclear Envelope

Answer 23

This is double membrane surrounding the nucleus which has pores it to allow the entry and exit of materials between the nucleus and the cytoplasm.

Question 24

Nucleolus

Answer 24

A small structure, one or more of which is found inside the nucleus; the nucleolus is usually visible as a densely stained body; its function is to manufacture ribosomes using the information in its own DNA.

Question 25

Nucleoli

Answer 25

Nucleolus (plural)

Question 26

Nucleosome

Answer 26

A bead-like structure made of eight histone molecules, around which DNA is wrapped; nucleosomes are the fundamental subunits of chromatin.

Question 27

Prophase

Answer 27

As Prophase begins the chromosomes are seen as loosely wound mass called Chromatin. In early Prophase the chromosomes condense and are seen to consist of two sister chromatids joined by centromere. The nucleolus breaks down and the centrioles begin to separate and start to form the spindle.

Question 28

DNA Replication

Answer 28

This is the process whereby DNA makes a copy of itself before mitosis begins so that there is a copy of each chromosome in the nucleus at the onset of mitosis. This occurs during the ‘S’ phase of interphase during the cell cycle.

Question 29

Spindle Fibre

Answer 29

When a cell divides the centrioles pull apart to produce a spindle of microtubules or fibres which are made of protein. These are called spindle fibres and are involved in the movement of the chromosomes during mitosis.

Question 30

Stem Cell

Answer 30

A relatively unspecialised cell that retains the ability to divide an unlimited number of times

Question 31

Telomere

Answer 31

Repetitve sequence of DNA at the end of chromosomes that protect gene from the chromosome shortening that happens at cell division.

Question 32

Telophase

Answer 32

The events of telophase are the reverse of those at prophase. Chromosomes lengthen and uncoil at the poles of the spindle and lose their visibility forming chromatin. The nuclear envelope reforms around the chromosomes and the nucleoli reappear. The spindle fibres break down.

Question 33

Adult Stem Cell

Answer 33

Adult stem cells are found in various tissues and organs in the body, in specialised location called 'niches'. They can only form some types of cells.

Question 34

Differentiation

Answer 34

Development into a more specialised cell type.

Question 35

Embryonic Stem Cell

Answer 35

Embryonic cells are found in the small hollow ball of cells (blastocyst) that forms shortly after fertilisation of an egg cell. They can form all cells in the human body. (they are pluripotent.)

Question 36

Fixation

Answer 36

.

Question 37

Multipotent

Answer 37

Having the ability to develop into a limited number of different cell types.

Question 38

Pluripotent

Answer 38

having the ability to develop into all cell lineages, except those related to non-embryonic tissues (such as the placenta and the umbilical)

Question 39

Potency

Answer 39

Power or ability

Question 40

Stem Cell Therapy

Answer 40

.

Question 41

Totipotent

Answer 41

.

Question 42

Cancer

Answer 42

A disease, often but not always treatable, that results from a breakdown in the usual control mechanisms that regulate cell division. Cells divide uncontrollably and form secondary tumours, from which cells may break away and form secondary tumours in other areas of the body in a process called matastasis.

Question 43

Carcinogen

Answer 43

Any agent that causes cancer.

Question 44

Mutagen

Answer 44

A factor that can cause a mutation. Some mutagens are carcinogen.

Question 45

Mutation

Answer 45

An unpredictable change in the structure of DNA, or in the structure and number of chromosomes.

Question 46

Oncogene

Answer 46

This is the name of a mutated gene which causes cancer.

Question 47

Primary Growth

Answer 47

A small group of tumour cells

Question 48

Tumour

Answer 48

An irregular mass of cells which results from uncontrolled mitosis of cells.

Question 49

Benign Tumour

Answer 49

A primary growth of tumour cells which do not spread from the site of origin but can compress and displace some of the surrounding tissues-for example ovarian cysts, warts and some brain tumour.

Question 50

Malignant Tumour

Answer 50

This is a cancerous tumour cells which spread from the site of origin to other parts of the body invading tissues and eventually destroying them. Cells can break off from a malignant tumour and spread through the circulatory and lymphatic system to other parts of the body to form secondary growth.

Question 51

Metastasis

Answer 51

Metastasis results from cells breaking away from a primary tumour and forming secondary tumours in other areas of the body.