Topic 4: The Cell Cycle Flashcards
Gametes
23 different chromosomes = haploid (n)
includes ova (eggs) + sperm
- sex cells
Somatic Cells
includes all cells of body except cells undergoing/resulting from meiosis
eg: muscle cell, nerve cell, etc.
46 chromosomes = diploid (2n)
= 23 homologous pairs
soma= body
Homologous Chromosomes
a chromosome pair (1 from each parent) that are identical in length, centromere position, and have genes for the same trait (e.g. eye colour) in the same location (locus)
Gene
a unit of heredity
= a region of DNA which contains information for synthesis of proteins
*how we pass on genetic info from one person to the next
alleles
different versions (alleles) of that gene that code for different versions of that trait.
§ e.g. blue eyes (chromosome from Dad), brown eyes
(chromosome from Mom)
What does each somatic cell contain?
23 different chromosome pairs
23 chromosomes from mom (ovum) paired with 23 chromosomes from dad (sperm)
= 46 chromosomes (diploid/2n somatic cell)
autosomal chromosomes (autosomes)
1 to 22
¦ contain genes for somatic characteristics
¦ e.g. hair and eye colour, height, etc
¦ each autosomal chromosome pair is not identical, but
equivalent= homologous chromosomes
sex chromosome
23
¦ contain genes that determine sex, XX=F XY=M
¦ X or Y from Dad
¦ X from Mom
What is the purpose of mitosis?
for growth + repair of tissues
to produce somatic cells
What does mitosis result in?
2 genetically identical daughter cells
List the stages of the cell cycle:
1) Interphase
2) Mitotic (M)/Cell Division phase
List the stages within Interphase:
G1,
S,
G2 phases
Interphase
chromosomes present as chromatin
normal cellular metabolic activities occurring e.g. protein synthesis
G1 Phase
growth, metabolism
centrosome replication begins
Note: in some cells that do not divide again once mature, (i.e. remain
in G1) – in these cells it is termed G0 phase
¦ e.g. nerve + some muscle cells
S Phase
chromosomes replicate, but are still present as chromatin (not individually visible)
ALWAYS occurs before division (mitosis and meiosis)
kinetochore proteins are produced
sister chromatids
replicates formed during S phase
centromere
area of DNA where sister chromatids attach to one another
kinetochore proteins
(produced during S phase) attach to each centromere to form the kinetochore
kinetochore
protein + DNA complex,
1/chromatid meaning 1 on each side)
site of attachment of spindle microtubules
G2 Phase
growth, metabolism
production of enzymes & other proteins needed for cell division
centrosome replication completed
What does the Mitotic Phase involve?
a) mitosis
b) cytokinesis
mitosis
= division of nuclear material (chromosomes)
4 phases, but continuous cycle!
i. Prophase
ii. Metaphase
iii. Anaphase
iv. Telophase
cytokinesis
division of cytoplasm
when mitotic phase ends:
mitosis & cytokinesis complete
daughter cells go into interphase (G1)
cycle starts over