Module 2:Cell Division Flashcards
How many stages are involved in the cell cycle?
What are they called?
3
interphase
mitosis(nuclear division)
cytokinesis(cell division)
How would you describe the cells produced from mitosis?
What can the cells be used for?
Do cells produced by mitosis give rise to genetic variation?
two genetically identical diploid daughter cells
for growth and asexual reproduction of cells
no
What happens during interphase and how many stages are there?
the cell grows , replicates its organelles and prepares to divide
three stages
What is the first stage and checkpoint within interphase?
G1-the cell grows and organelles replicate
G1 checkpoint-if cell meets requirements it is triggered to begin DNA replication , if not it enters the G0 phase (cell leaves the cycle)
What is the second phase within interphase?
S phase- DNA (chromosomes) are replicated
What is the last stage and other checkpoint within interphase?
G2-cell continues to grow , energy stores increase and DNA checked for errors
G2 checkpoint-checks cell size and checks DNA for errors
What are the 4 stages of mitosis?
prophase , metaphase , anaphase , telophase
What happens during prophase?
3 points
nuclear envelope broken down
chromosomes condense
centrioles move to opp poles of the cell for spindle fibre formation
What happens during metaphase?
chromosomes line up along metaphase plate in the centre of the cell and attach to spindle fibres via centromeres
What happens during anaphase?
sister chromatids are separated at their centromere and spindle fibres pull them to opp ends of the cell
What happens during telophase?
chromatids arrive at poles
new nuclear envelope formed
chromatids condense and join up to become homologous pairs again
What happens during cytokinesis?
cytoplasm and cell membrane divide to produce 2 daughter cells
What is an allele ?
What is a homologous pair?
allele-a different version of the same gene
homologous pair-matching set of chromosomes
How would you describe the cells produced by meiosis?
How many times does division occur within one cycle?
four genetically non identical haploid gametes
2 times
Does meiosis give rise to genetic variation , if so how?
yes
through crossing over of chromatids
through independent assortment of chromosomes
What happens during prophase 1 ?
6 points
chromosomes condense
homologous chromosomes form bivalents
crossing over takes place
nuclear envelope disintegrates
spindle fibres form
replication occurs
What is a bivalent?
made up of a pair of homologous chromosomes , has 2 chromosomes and four chromatids
What happens during metaphase 1 ?
homologous chromosomes arrange at metaphase plate and independent assortment occurs
What happens during anaphase 1?
spindle fibres attach to centromeres and chromosomes are pulled to either poles of the cell
What happens during telophase 1 ?
nuclear envelope reforms
cytokinesis occurs to produce 2 haploid cells
What happens during prophase 2?
chromosomes recoil and condense
nuclear envelope disintegrates again
What happens during metaphase 2 ?
individual chromosomes assemble at the metaphase plate and independent assortment occurs
What happens during anaphase 2 ?
spindle fibres attach to centromeres and contract , separating sister chromatids and pulling them to either poles of the cell
What happens during telophase 2 ?
nucleolus becomes visible
nuclear envelope reforms
cytokinesis occurs producing four unique haploid cells
Whats the main difference between meiosis 1 and 2?
1-whole chromosomes are pulled apart from their homologous pairs
2-sister chromatids are pulled apart
