Mitosis And Meiosis Flashcards
What is a p arm?
Short arm of chromatid
What is the q arm?
Long arm of chromatid
What is a telomere?
Repeated sequences at each end of a chromosome or chromatid
What is a centromere?
Repetitive sequence that links sister chromatids
What are the positions of centromeres called?
Metacentric- middle
Submetacentric
Afrocentric
Telcentric- top
How are chromosomes grouped?
According to size and shaped
In groups A-G
What is mitosis?
Cell division in somatic cells
Produces two identical daughter cells
What tissues is mitosis necessary for?
Epidermis
Mucosae
Bone marrow
Spermatogonia
What occurs in prophase?
Spindle fibres appear
chromosomes condense
Nuclear membrane breaks down
What occurs in prometaphase?
Spindle fibres attach to chromosomes
Chromosomes condense
What happens in metaphase?
Chromosomes align at the equator
What happens at anaphase?
Centromeres divide
Sister chromatids move to opposite poles
What happens in telophase?
Nuclear membrane reforms
Spindle fibres disappear
Chromosomes decondense
What happens in cytokinesis?
Cytoplasm divides
2 genetically identical daughter cells form
What are alleles?
Different forms of the same gene
Where are chromosomes during interphase?
Chromosome territories
What alleles do sister chromosomes have?
The same
What is meiosis?
Cell division for germ line cells Produces 4 non-identical cells Haploid One round of replication and two rounds of division Egg and sperm produced
What occurs in prophase I?
Nuclear membrane breaks down
Chromosomes condense
Crossing over occurs
What occurs in metaphase I?
Pairs of homologous chromosomes move to the equator of the cell
What occurs in Anaphase I?
Homologous chromosomes move to opposite poles of the cell
What occurs in telophase I?
Chromosomes gather at poles of the cell
What occurs in prophase II?
New spindle forms
What occurs in metaphase II?
Chromosomes line up at the equator
What happens in anaphase II?
Centromeres divide and chromatids move to opposite poles of the cell
What happens in telophase II?
Nuclear envelope reforms
How does genetic diversity occur?
Random assortment of chromosomes
Crossing over of genetic material
What is spermatogenesis?
Cell division to produce male gametes
1 cell (spermatocyte)- 4 sperm
Takes around 60 days
What is oogenesis?
Cell division to produce female gametes
1 cell (oocyte) - 1 egg and 3 polar bodies
Takes 12-50 years
What are the consequences of missegregation in meiosis?
Third of miscarriages
Infertility
Mental retardation
What is non-dysfunction at anaphase?
Where the incorrect number of chromosomes is moved to each pole
1 cell gets 2 chromosomes
1 cell gets 0 chromosomes
Leads to aneuploidy
What is the format to describe a karyotype?
Chromosome number, sex complement and structural changes separated by commas
E.g. 47, XY, +21
Male with trisomy 21
What does mitotic dysfunction in first post zygote can division lead to?
One with less chromosomes Usually lost unless involved X
If non disjunction occurs in later cell divisions
Leads to mosaic karyotype
What is mosaicism?
Presence of two or more cell lines in an individual
