the cell cycle

Question 1

what are the 2 different types of cells based on

Answer 1

chromosome content

Question 2

2 cell types?

Answer 2

gametes

somatic cells

Question 3

gametes

Answer 3

23 different chromosomes=haploid (n)
includes ova (eggs) and sperm

Question 4

somatic cells

Answer 4

-includes all cells of body except cell undergoing/resulting from meiosis
-46 chromosomes = diploid (2n)
-23 homologous pairs
each somatic cell contains 23 different chromosome pairs (23 chromosomes from mom (ovum) pairs with 23 chromosomes from dad (sperm) = 46 chromosomes (diploid = 2n)
-chromosomes and chromosome pairs are numbered 1-23:
a) 1 to 22 = autosomal chromosomes (autosomes)
-contain genes for somatic characteristics
eg. hair and eye colour, height
-each autosomal chromosome pair is not identical, but equivalent = homologous chromosomes
b)23 = sex chromosome
-contain genes that determine sex, XX=F and XY=M
-X or Y from Dad
-X from mo

Question 5

homologous chromosomes

Answer 5

a chromosome pair (1 from each parent) that are identical in length, centromere position, and have genes for the same trait (eye colour) in the same location (locus)

• but may have different versions (alleles) of that gene that code for different version of that trait
  eg. blue eyes (chromosome from Dad), brown eyes (chromosome from mom)

Question 6

gene

Answer 6

a unit of heredity= a region of DNA which contains info for synthesis of proteins

Question 7

cell cycle

Answer 7

for growth and repair of tissues

• somatic “parent” cell 2n -> 2 genetically identical somatic daughter cells 2n
• 2 stages : interphase and mitotic phase

Question 8

interphase

Answer 8

• chromosomes present as chromatin
• normal cellular metabolic activities occurring eg. protein synthesis
• G1, S, and G2

Question 9

G1

Answer 9

• growth, metabolism
• at end of G1, centrosomes replicate
• in some cells that do not divide again once mature (ie. remain in G1)- in these cells it is termed G0 phase
  eg. nerve and some muscle cells

Question 10

S

Answer 10

• chromosome replicate but are still present as chromatin (not individually visible)
• always occurs before division (mitosis and meiosis)
• replicates are called sister chromatids
• attached to each other as an area of DNA called the centromere
• kinetochore proteins (produced during S phase ) attach to each centromere to form the kinetochore (=protein + DNA complex, 1/ chromatid)

Question 11

kinetochore

Answer 11

site of attachment of spindle microtubules

Question 12

G2

Answer 12

Growth, metabolism

-production of enzymes and other proteins needed for cell division

Question 13

mitotic phase

Answer 13

-mitosis= divisions of nuclear material (chromosomes)
-4 phases, but continuous cycles
prophase, metaphase, anaphase, telophase
-cytokinesis= division of cytoplasm

Question 14

when mitotic phase ends

Answer 14

• mitosis and cytokinesis complete
• daughter cell go into interphase G1
• cycle starts over