Chapter 12

Question 1

Genome

Answer 1

Genetic information is called genome

Question 2

Length of a typically DNA

Answer 2

A typical human cell for example has 2m of DNA -a length about 250000 times greater than diameter

Question 3

Chromosomes

Answer 3

Chromosomes help in replication and distribution of DNA

Question 4

Chromatin

Answer 4

The entire complex of DNA and protein that is the building material of chromosomes is referred to as chromatin.

Question 5

Somatic cells

Answer 5

All body cells excepts reproductive cell. Contain 46 chromosomes made up of two set 23 chromosomes.

Question 6

Gametes

Answer 6

Reproductive cell

Question 7

Sister Chromatids

Answer 7

Joined copies or original chromosomes. The two chromatids are identical DNA and are initially attached along length by protein complexes cohesion.

Question 8

Centromeres

Answer 8

A region of chromosomal DNA where the chromatid is attached most closely to its sisterbchromatid

Question 9

Cytokinesis

Answer 9

The division of cytoplasm

Question 10

Meiosis

Answer 10

Yield daughter cell with only one set of chromosomes, half as many chromosomes as the parent cells. In human occur only in special cell in ovaries or testes. The number of chromosomes is double back during fertilisation.

Question 11

Mitotic (M) phase

Answer 11

Includes both mitosis and cytokinesis. Is the shortest part in cell cycle

Question 12

Inter phase

Answer 12

Is subdivided I’m G1 (first gap)phase , S (synthesis)phase and G2( second gap)phase.
During G phase the cell grows.. duplication occur during S phase

Question 13

Order of cell cycle

Answer 13

Cell grows (G1 phase) -> Dublication occur (S phase ) -> Cell browns with dublicated chromosomes (G2 phase)-> mitosis occur (M phase). It takes 24 hour to complete a cycle in human.

Question 14

Stages of Mitosis

Answer 14

Mitosis is conventionally broken down into five stages prophase,prometaphase,metaphase, anaphase, telophase

Question 15

G2 of inter phase

Answer 15

• a nuclear envelope encloses nucleus
• the nucleus contain one or two nucleoli
• two centrosome have formed by duplication.
• chromosomes duplicated during S phase.

Question 16

Prophase

Answer 16

• the chromatin fibre coils, condense. Into discrete chromosomes
• the nucleoli disappear
• each duplicates chromosomes appear as two identical sister chromatid joined at their centromeres
• the mitotic spindle begins to form.

Question 17

Prometaphase

Answer 17

• nuclear envelope fragments
• the microtubules extending from each centrosome can now invade the nuclear area,
• the chromosomes have even condensed more
• each of the chromosomes their own kineticchores
• nonkinetochore microtules interact with those from opposite poles of the spindle

Question 18

Metaphase

Answer 18

• the centrosomes are now at opposite pole of the cell
• the chromosomes have arrived on metaphase plate that is equidistant between spindle and two poles
• for each chromosomes, the kineticchores of the sister chromatid are attached kineticchores microtubules coming from opposite poles

Question 19

Anaphase

Answer 19

• shortest stage last only few minutes
• begins when cohesion protein are cleaved, allowing the sister chromatid to separate
• the two liberated chromosomes move to opposite ends of their cell as kineticchores are shorten. Centromeres moves first as they are attached to kineticchores.
• the cell elongates as the nonkinetochores lengthen
• by the end, two cell have equivalent and complete collection of chromosomes

Question 20

Telophase

Answer 20

• nuclear envelope arises
• nucleoli reappear
• chromosomes become less condense
• remaining spindle depolymerises
• mitosis is complete

Question 21

Cytokinesis

Answer 21

• in animal cell,cytokinesis involves formation of cleavage furrow which pinched the cell into two
• in plant cells a cell plate forms

Question 22

Centromeres

Answer 22

A sub cellular region containing material that function throughout the cell cycle to organise cells microtubules.

Question 23

Aster

Answer 23

A radical array of short microtubules, extend from each centrosome

Question 24

Kineticochores

Answer 24

A tru true made up of protein have assemble a specific section of DNA at each centromeres.

Question 25

Meta phase plate

Answer 25

An imaginary plate rather than an actual plate at the centre

Question 26

Cleavage furrow

Answer 26

A shallow groove in the cell surface near the old metaphase plate

Question 27

Binary fision

Answer 27

Meaning the division in half , refer to process and to the asexual reproduction of single -called eukaryotes

Question 28

Origin of replication

Answer 28

When the DNA of the bacterial chromosome begins to replicate at a specific place on the chromosome called the origin of replication

Question 29

Stages of binary fission in bacteria

Answer 29

1-chromosome replication begins. Soon after, one copy of the origin moves rapidly toward the other end of cell using actin like prog 2- replication continues. One copy of the origin is now at the end of the cell 3-replication finishes. The plasma me,brand is pinched inward by a tub,in-like protein,and a new cell wall is deposited 4-two daughter cell result.

Question 30

Cell cycle control system

Answer 30

Cell cycle control system is The sequential events of the cell cycle are directed by distinct. It is operated set of molecules in the cell that both trigger and cooordinate event.,

Question 31

Check point

Answer 31

Is a control point in the cell cycle where stop and go-ahead can regulate the cycle

Question 32

Cyclin

Answer 32

A protein that get its name from its cyclically fluctuating concentration in the cell

Question 33

CDK

Answer 33

Cyclin dependent kinases

Question 34

Molecular mechanisms that help regulate the cell cycle

Answer 34

- synthesis of cyclin begins in late S phase end continues through G2. Because cyclin is protected from dehydration during this stage, it accumulates - cyclin combines with CDK, producing MPF. When enough MPF molecules accumulate, the cell passes the G2 checkpoint and begins mitosis. - MPF promotes mitosis by phosphorylating various proteins.MPF activity peaks during metaphase - during anaphase cyclin component of MPF is degraded terminating M phase . The cell enter G1 - during G1, the degraded the cyclin continues cdk components of MPF is recycled

Question 35

Growth factor

Answer 35

Protein released by certain cell that stimulates other cell to divide.

Question 36

Density dependent inhibitors

Answer 36

A phenomenon in which crowded cell stop dividing

Question 37

Anchorage dependence

Answer 37

To divide they must attach to a substratum, such as inside of a culture flask or extracellular matrix of a tissue

Question 38

Transformation

Answer 38

The process that causes cell to behave like cancer cells

Question 39

The growth of metastasis

Answer 39

- a tumour grows from signal cancer cell - cancer cells invade neighbouring tissues - cancer cells spread through lymph and blood vessel to other parts of the body - a small percentage of cancer cells may metastasis to other body

Question 40

Benign tumour

Answer 40

Do not cause serious problem and can be completely removed by surgery

Question 41

Malignant tumour

Answer 41

Includes cell whose genetic and cellular changes enable them to spread to new tissue and impair the function of one or more organ

Question 42

Metastasis

Answer 42

Spread of cancer cells to locations distant from their original site is called metastasis

Question 43

Cell division

Answer 43

Unicellular organism reproduce by cell division multicellular depend on cell division for development

Question 44

Cell cycle

Answer 44

An ordered sequence of events i the life of a cell from its origin until it divides into daughter cell