Lecture 14 Flashcards
What is the difference between prokaryotic and eukaryotic chromosomes?
Prokaryotic = circular
Eukaryotic = linear
What is a karyotype?
- visual representation of chromosomes
- from metaphase
- in homologous pairs
What is the definition of a homologous chromosome?
A pair of chromosomes with the same genes, one from the mother and one from the father.
What is a locus?
The location of a gene
What is an allele?
An alternative version of a gene
What are the phases of the cell cycle and what is the purpose of each phase?
- mitotic phase (mitosis + cytokinesis)
Interphase has 3 phases. - G1 phase (metabolic activity +growth)
- S phase (metabolic activity, growth + DNA synthesis)
- G2 phase (metabolic activity, growth + prep for cell division_
What is the definition of mitosis?
The distribution of chromosomes into two daughter nuclei.
What is the definition of cytokinesis?
The division of cytoplasm, producing 2 daughter cells.
What happens during the G2 phase of interphase?
- prepping for cell division
- nuclear envelope = intact
- nucleolus = visible
- 2 centrosomes formed
- cannot see duplicated chromosomes as not yet condensed
What is the order of the steps of mitosis?
PPMATC (prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis)
What happens during prophase?
- nucleoli disappear
- duplicated chromosomes condense, creating sister chromatids joined with a centromere
- mitotic spindle starts to form
- microtubules lengthen the cell
- centrosomes go towards opposite sides of the cell
What happens during prometaphase?
- nuclear envelope breaks down
- kinetochore proteins form at centromeres for kinetochore microtubules to attach
- non-kinetochore microtubules continue to lengthen the cell
What happens during metaphase?
- centrosomes are at the two different poles
- kinetochore microtubules attached to all centromeres
- chromosomes lined up on metaphase plate, with centromeres above line (equal distance from centrosomes)
What happens during anaphase?
- sister chromatids disjoin at centromere
- each chromatid becomes individual daughter chromosome
- kinetochore microtubules shorten, bringing daughter chromatids to opposite sides
- non-kinetochore microtubules continue to lengthen cell
- anaphase ends when each pole has a complete collection of chromosomes
What happens during telophase?
- chromosomes become less condensed
- spindle microtubules break down
- 2 daughter nuclei with nuclear envelope form, nucleoli reappear
- mitosis is complete
What happens during cytokinesis?
- cytoplasm divides, resulting in two daughter cells
- in animals, form of cleavage furrow which pinches the cell into two
- in plant cells, forms a cell plate between the daughter cells
