Chapter 2 Flashcards
Amount (length) of DNA in one human cell
6 ft
Haploid (n)
one copy of a genome distributed among chromosomes
Diploid (2n)
two copies of a genome distributed among chromosomes
How many chromosomes do humans have
46 (23 pairs)
Homologous chromosomes
paired chromosomes that carry the same genes (one from each parent)
Metacentric
centromere is at center of chromosome, so it appears to have 2 equal halves.
Submetacentric
one arm is longer than the other
Areocentric
one arm has a stalk and often with a bulb (satellite) on it
Telocentric
only one arm bc the centromere is at the end (not found in humans)
chromatid
one copy of a newly replicated chromosome
sister chromatids
exact copies of chromosome (duplicated) held together by centromeres
Daughter chromosomes
separated sister chromatids
Where is DNA located on a chromosome
Locus
G1
cellular contents (not chromosomes) are duplicated
S
each of the 46 chromosomes is duplicated by the cell
G2
cell double checks the duplicated chromosomes for error
What does mitosis result in
2 identical daughter cells
Prophase
- condensation of chromosomes
- nucleolus shrinks
- centrioles move apart
- mitotic spindle assembles
Prometaphase
- nuclear envelope breaks down
- spindle enters nuclear area
- kinetochore microtubules attach to kinetochores on sister chromatids
Metaphase
- kinetochore microtubules align the chromosomes
Anaphase
- joined centromeres of sister chromatids separate
- daughter chromosomes move towards opposite poles
Telophase
- chromosome uncoils
- nuclear envelope forms around chromosomes
- spindle appears and nucleolus reforms
Cytokinesis
cytoplasm divides and parent cell becomes 2 daughter cells
when does cytokinesis occur
begins during anaphase and continues through telophase
mitosis Mnemonics
Idiot, Please Pass Me Another Tequila
How many unique gametes (n) can a cell with M pairs of chromosomes make?
M^n
Which Meiosis stage is similar to mitosis
Meiosis II
Prophase I
- Leptonema
- Zygonema
- Pachynema
- Diplonema
- Diakinesis
Leptonema
Condensation of chromosomes (early)
Zygonema
homologous pairs align with eachother (early to middle)
Pachynema
Homologous regions of nucleotides swap (tetrads cross over) (middle)
Diplonema
Disassembly of synaptonemal complex (middle to late)
pseudoautosomal regions
small regions that are homologous where crossing over occurs
Meiosis prophase I Mnemonic
Lost Zombie Parts Dont Die
Prometaphase I
- nucleolus disappears
- nuclear envelope breaks down
- spindle enters former nuclear area
- Kinetochore microtubules on one end attach to both Kinetochores
Metaphase I
Kinetochore microtubules align tetrads at the metaphase plate
Anaphase I
Chromosomes of each tetrad separate, migrate towards opposite poles (Dyad)
Sister chromatids in Meiosis 1
DO not separate
Telophase 1
- Dyads complete migration to poles
- spindle disapears
- nuclear envelope forms
- cytokinesis
How is down syndrome detected
Karyotyping
Kinetochores
protein complex assembled on centromeres
