Lecture 12 Flashcards
What is a Karyotype
An ordered visual representation of the chromosomes in a cell
What is the locus
Location of a gene on chromosome
what is an allele
a different version of a gene
what does homozygote mean
Same allele
What does heterozygote
different allele
what are Autosomes
1-22 homologous pairs
What are the sex chromosomes
the X and Y chromosomes
What do multicellular organisms depend on cell division for
development from a fertilized cell
growth to adult
repair
What is the cell cycle
Interphase, G, S (DNA synthesis), G2
mitotic phase- mitosis, cytokinesis
What happens in G2 of interphase
Nuclear envelope encloses the nucleus (one or more nucleoli contained)
two centrosome form from single (organize microtubules of the spindle)
chromosomes duplicated during 2 phase
What happens in prophase
chromatin fibres become more tightly coiled
nucleoli disappear
duplicated chromosomes appear as sister chromatids
miotic spindle forms (from centromere)
Centrosome move away from each other
What happens in prometaphase
nuclear envelope fragments
microtubules can invade the nuclear area
chromosomes more condensed
each chromatid has kinetochore that (kinetochore) microtubules attach to
other microtubules interact with opposite spindle
What happens in Metaphase
Centromere at opposite poles of cells
Chromosomes lined along the metaphase plate
Kinetochore from each centromere attached to sister chromosomes
What happens in Anaphase
Cohesion proteins cleaved to allow sister chromosomes to split into full chromosomes
move towards netromeres as kinetochore microtubules shorten
cell elongates as nonkinetochore microtubules lengthen
ends of cells have an equal chromosome number
What happens in Telophase
two daughter nuclei form nuclear envelope from parent fragments nucleoli reappear chromosomes become less condensed spindle microtubules are depolymerized mitosis complete
