Mitosis Flashcards
Gametes
23 different chromosomes = Haploid (n)
includes ova (eggs and sperm)
Somatic Cells
What type of cell is this? how many chromosomes?
46 chromosomes = Diploid (2n)
- 23 homologous pairs
all cells of body except the cells that undergo meiosis
ex) muscle cells or nerve cells etc
Gene
Define
unit of heredity = a region of DNA that most often contains info for synthesis of proteins
Homologous chromosomes
What do homologous chromosomes contain..?
a chromosome pair (1 from each parent):
both chromosomes are similar in:
1) length
2) centromere position
3) genes for the same trait (e.g eye color) in the same location (locus) BUT
4) may have 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)
2 cell types that are based on chromosome content
gametes and somatic cells
How many chromosomes are in each somatic cell?
Per somatic cell and from each parent
23 different chromosomes in each somatic cell
- 23 from mom (ovum) paired with 23 from dad (sperm)
= 46 chromosome pairs (diploid,2n in a somatic cell)
Autosomal chromosomes (autosomes)
Genes? What are they
Numbers 1 to 22
contain genes for somatic characteristics
e.g hair colour, eye colour, height, etc.
Each autosomal chromosome pair is not identical but equivalent = Homologous chromosomes
How many chromosome pairs are there? What are the pair numbers and the names of the chromosomes?
23
chromosome and chromosome pairs are numbered 1-23
#1-22 = autosomal chromosomes
#23 = sex chromosomes
Sex chromosomes
Genes?
23
genes that determines sex
XX = female, x from mom
XY = male, x or y from dad
What the purpose of the cell cycle?
What type of cell is in the cell cycle?
for growth and repair of tissues in our bodies
to do that we have a somatic “parent” cell (2n) -> gives rise to 2 genetically identical somatic “daughter” cells (2n)
Diploid
2n = 46 chromosomes
containing 23 homologous chromosomes
Haploid
“n” = 23 different chromosomes
What are the two stages of the cell cycle?
1) Interphase (G1, S, G2) - makes up a majority of the cell cycle
2) Mitosis (p,m,a,t)
Interphase
in this phase, chromosomes are present as chromatin (dispersed, uncoilded when cell isnt dividing yet)
growth
DNA replication
normal cellular metabolic activities occur
Phases: G1 (or G0), Synthesis Phase and G2
G1 Phase
Growth, metabolism
at the end of G1, centrosomes begin to replicate
G0 (Gnot) = once mature, most cells do not divide again e.g muscle cells or neuron cells (remain permanently in G1)
S Phase (Synthesis phase)
What is replicated, and being formed in this phase?
DNA replication!
chromosomes replicate, still present as chromatin (not individually visible), sister chromatid replicate (attach to eachother at the centromere), ALWAYS occur before division (mitosis or meiosis)
Kinetochore proteins are also produced, attach to each centromere to form kinetochore
STILL ONE CHROMOSOME in this phase
Kinetochore proteins
Which phase is it formed in?
Formed in the S phase, attached to each centromeres to form kinetochore (=protein + DNA comples, 1/chromatid)
Kinetochore
kinetochore is made up of kinetochore proteins and centromere (1 per chromatid)
The kinetochores is the site of attachment for spindle microtubules
- forms centrosomes
- protein and DNA complex
G2 Phase
Preps itself to get into M phase
- cell growth continues, metabolism
Production of enzymes and other proteins needed for cell division
CENTROSOMES complete replication (replicate in G1 then COMPLETE in G2)
What does the mitotic phase involve?
Mitosis (division of nuclear material such as chromosomes) and cytokinesis (division of cytoplasm)
4 phases of mitosis, but it is continuous
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
What is mitosis?
Division of nuclear material (chromosomes)
4 phases: Prophase,metaphase, anaphase and telophase
Cytokinesis
Division of cytoplasm
What happens to the daughter cells when the mitotic phase ends?
So, both mitosis and cytokinesis is complete
Then the daughter cells from mitosis go into interphase (G1)
- however, daughter cells either mature (G0) or continue into another cell cycle
cycle starts over
What are the steps prior to mitosis
Interphase (G1 or G0, S phase, G2)
