Chapter 4a: Chromosomal Basis of Heredity Flashcards
- single chromosome plus plasmids
prokaryotes
copies its chromosome and divides immediately afterward
prokaryotes
circular chromosome
prokaryotes
Chromosome made only of DNA
prokaryotes
chromosome found in the cytoplasm
prokaryotes
have many chromosomes
eukaryotes
have linear chromosomes
eukaryotes
chromosomes made of chromatin, a nucleoprotein (DNA coiled around histone proteins)
eukaryotes
chromosomes found in a nucleus
eukaryotes
copies chromosomes, then the cell grows, then goes through mitosis to organize chromosomes in two equal groups
eukaryotes
chromosomes condensed and visible during cell division
eukaryotes
Chromosomes of eukaryotes: At the beginning of mitosis they can be seen to consist of two threads (__) joined by a __
- sister chromatids
- centromere
The sister chromatids are __ copies
identical
Parts of eukaryotic chromosome
- p arm (petite)
- centromere
- q arm
- telomere
__ is a specific region of the eukaryotic chromosome where the __ (the complex of DNA and proteins to which the spindle fibers) attach and pull the chromosomes during both mitosis and meiosis
- centromere
- kinetochore
types of chromosomes based on centromeric position
- metacentric
- submetacentric
- acrocentric
- telocentric
centromere is median
metacentric
centromere is submedian
Submetacentric
centromere is subterminal
acrocentric
centromere is terminal
telocentric
protects the end of the chromosome from deterioration
telomere
length shortens with age
telomere
GT rich repetitive sequences at the ends of the chromosomes
telomere
daughter chromatids are bound at the __
centromere
where microtubules attach during mitosis (more later)
kinetochore
telomeres at the ends of chromosome are __ sequence (__ - __ times), maintained by __
- TTAGGG
- 500-3000
- telomerase
__(phase): Multicellular organisms __ their chromosomes before cell division
: They must __ to a mature size.
: The nucleus divides, distributing the chromosomes into two equal groups (__)
- interphase
- copy
- grow
- mitosis
The cytoplasm then divides (__) each part taking a nucleus.
cytokinesis
The Cell Cycle
Interphase:
Gap 1 (G1) - Cell grows
Synthesis Phase - Replication of DNA
Gap 2 (G2) - cell prepares to divide
Mitotic Phase (M) - cell division
Gap Zero (G0) Phase - Quiescent state
organelles and molecules required for cell division are produced. Cell prepares for mitosis.
Gap 2 (G2) Phase
§ results in the production of two daughter cells from a single parent cell
§ The daughter cells are identical to one another and to the original parent cell.
mitosis
- Results in the production of germ (sex) cells
- halves the number of chromosomes
- picks one chromosome from each pair at random and places them in a sex cell. This results in enormous variation amongst the sex cells.
meiosis
Meiosis: chromosome number?
halved
Meiosis: daughter cells?
four
Meiosis: genetic variation?
cross over
Stages of mitosis
- prophase
- metaphase
- anaphase
- telophase
- cytoknesis
Mitosis: Chromosomes condense.
prophase
Mitosis: Chromosomes align at the equator.
metaphase
Mitosis: Sister chromatids separate.
anaphase
Mitosis: Nuclear envelope reforms.
telophase
Stage in prophase where chromosomes continue to condense and become visible.
leptotene or leptonema (thin thread stage)
The process of pairing of chromosomes
synapsis
Stage in prophase where crossing over occurs between homologous chromosomes.
Pachytene (thickening stage)
Stage in prophase where homologous chromosomes begin to pair up and become visible as pairs.
zygotene (pairing stage) or zygonema
stages of Prophase I
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis
characterized by desynapsis and chiasmata formation.
Diplotene (duplication stage) or diplonema
Stage in prophase where nuclear envelope breakdown and spindle formation continue.
Diakinesis (moving apart stage)
crossing over =
recombination
What is the term for the site of crossing over between non-sister chromatids during meiosis?
chiasma
Stage where genetic material is exchanged between homologous chromosomes?
prophase I
Stage where homologous chromosomes align independently at the cell’s equator?
metaphase I
Stage where homologous chromosomes separate and move towards opposite poles?
anaphase I
Stage where nuclear envelopes form around each set of chromosomes?
Telophase I
Stage where chromosomes condense again and spindle fibers form?
Prophase II
Stage where chromosomes align at the cell’s equator?
metaphase II
Stage where sister chromatids separate and move towards opposite poles?
anaphase II
Stage where nuclear envelopes form around each set of chromatids and cytokinesis occurs?
telophase II
