W7L2 - Cell Division and Reproduction Flashcards
(25 cards)
Why do cells divide?
Growth, Repair, Reproduction
What is mitosis involved in
Growth, Repair, Regeneration and reproduction of unicellular eukaryotes
How do prokayotes reproduce
binary fission
How do multicellular organisms reproduce ?
Meiosis
What are histones
balls of proteins that the double helix strand winds to
Why is histone important in DNA
it gives structure to DNA so that it keeps it organised and not tangled up
What does interphase do
growth and replication of cellular component
What is mitotic phase
where the cell divides its copied DNA and cytoplasm to make two new cells
What is cytokinesis
division of the cytoplasm where a cleavage furrow splits into 2 daughter cells
What is a cleavage furrow
indentation that forms on the surface of an animal cells that is about to separate
What is the cleavage furrow made up of
a contracting ring of actin microfilaments and myosin
What is the difference between cytokinesis in a plant cell and an animal cell
Plant cells have rigid walls, therefore no cleavage furrows instead a cell plate is formed in the middle
What is apoptosis
Programmed cell death -> remove unwanted cells during development
Explain apoptosis in developing mouse paws
mouse paws usually have webbed hands but via apoptosis fingers are produced.
What happens in G2 of Interphase
Chromosomes are duplicated but uncondensed and centrosomes are present
What happens in prophase in Mitosis
Two sister chromatids of one chromosome present, individual chromosomes more visible and centrosomes are further apart
What occurs in pro metaphase in Mitosis
Nuclear membrane degraded, chromosomes are free, spindle fibres (kinetochore microtubules) attach to centromere
What happens in metaphase in mitosis
chromosomes align in the middle and centrosomes end up at the opposite ends of the cell
What happens in anaphase in mitosis
The chromosomes get pulled apart creating new daughter chromosomes
What occurs in telophase and cytokinesis in mitosis
cleavage furrow is created, splitting cell, nucleolus is forming and nuclear envelope develops
What happens in Prophase I in Meiosis I
Crossing over occurs and pairs of homologous chromosomes held together by chiasma
What occurs in Metaphase I in MEIOSIS
Pairs of homologous chromosomes line up at the metaphase plate -> independent assortment occurs
What occurs in anaphase I in meiosis
Homologous chromosomes separate and sister chromatids remain attached at the centromere
What occurs in Telophase I and Cytokinesis
two new cells form, each with half the chromosome number 2n -> n
