Genes and Heredity Flashcards
Define haploid cell.
A cell with only one set (1 of each type) of chromosomes (where n = # different chromosomes).
How many molecules of DNA are in a single stranded chromosome?
1 molecule of DNA.
How many molecules of DNA are in a double stranded chromosome?
2 molecules of DNA.
What are homologous chromosomes?
Same size, same shape, same genes, but not on the same chromosome (2 different chromosomes).
What is the ploidy level of trisomy?
2n+1
Name the possible changes in chromosome structure.
Inversion, translocation, deletion, and duplication.
You have 4 different ss chromosomes in 1 cell. What is the ploidy level?
1n (1 of each type).
You have 4 different ds chromosomes in 1 cell. What is the ploidy level?
1n (1 of each type even if ds).
Name the functions of mitosis.
Growth, repair, asexual reproduction, division to produce new cells. (aging, cancer, immunity)
What are the stages of the cell cycle?
1-Interphase (G1, S-phase, G2), 2-mitosis, 3-cytokinesis.
What is the 1st checkpoint, what does it check for and what does it engage?
G1/S checkpoint: checks if cell double in size, growth rate is adequate and presence of growth factors.
-SPF is activated
What does SPF do?
The S-phase promoting factor (SPF) initiates the S-phase, DNA replication occurs and SS chromosomes turn into DS chromosomes.
What is the 2nd checkpoint, what does it check for and what does it engage?
G2/M checkpoint: checks if the DNA replication was complete and successful, checks the cell mass, the cell contents, the growth rate and the time elapsed.
-MPF is activated
What does MPF do?
The mitosis promoting factor (MPF) initiates chromatin condensing into chromosomes, breakdown of the nuclear membrane and the assembly of mitotic spindle.
What is the 3rd checkpoint, what does it check for and what does it engage?
The mitotic spindle checkpoint checks is all kinetochores are attached to spindle fibers correctly.
-APC is activated
What does APC do ?
The anaphase promoting complex allows chromatids to separate and inactivates MPF so it allows the chromosomes to de-condense and the spindle fibers to breakdown.
What are the phases of mitosis?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
How are genes inherited?
In gametes via sexual reproduction.
What is a centriole?
A cylinder composed of microtubules.
What is a centromere?
Highly condensed area of a chromosome, appears as a constriction.
What is a centrosome?
Organelle that creates microtubules.
Define condensin.
Proteins that help chromatin condense into chromosomes.
Define histones.
Proteins found in chromatin.
Define cohesins.
Proteins that hold sister chromatids together.
True or False: Mitosis only occurs in diploid cells?
False, it can occur in any cell.
True or False: Centrioles are in all eukaryotic cells?
False, there are none in plants.
True or False: Prokaryotes are not haploid.
True, haploid refers to eukaryotes only.
Define meiosis.
A type of cell division (sexual) that produces 4 unique haploid cells called gametes. It is composed of 2 sets of division.
What are the stages of meiosis?
- Interphase (G1, S-phase, G2)
- Meiosis I
- Interkinesis (interphase without S-phase)
- Meiosis II
- Cytokinesis
What are the stages meiosis I?
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I
What are the stages meiosis II?
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II
What are the functions of meiosis?
Create haploid gamete (egg and sperm) necessary for sexual reproduction, create genetic variation.
How does meiosis create genetic variation?
- Crossing-over between homologous pairs during Prophase I
- Independent assortment of homologues in meiosis I
- Random fertilization variation created by sexual reproduction
True or False: homologous chromosomes are paired in meiosis, but not in mitosis?
True.
Mosquitoes n=3. How many ds chromosomes are in each cell in G1?
- G1 precedes DNA replication so chr are ss.
Mosquitoes n=3. How many chromosomes are in Prophase I?
- Prophase I is diploid.
Mosquitoes n=3. How many chromatids are in Prophase I?
- Diploid and double-stranded.
Mosquitoes n=3. How many sets of chromosomes are in a cell in Metaphase I?
- Diploid so 2 of each types, do 2 sets.
Which features are present in Metaphase & Metaphase I?
DS chromosomes, homologous chromosomes, spindle fibers, kinetochores and centrosomes.
Which features are present in Metaphase I & Metaphase II?
DS chromosomes, spindle fibers, kinetochores and centrosomes.
During which phase do chromosomes align at the center of the cell?
In Metaphase & Metaphase II. Not in Metaphase I: tetrads align at the center.
During which phase is the ploidy level 2n?
G1, G2, Prophase, Prophase I, Metaphase, Metaphase I, Anaphase I & II.
During which phase are homologous chromosomes present?
G1, G2, Prophase, Prophase I, Metaphase, Metaphase I.
Define phenotype.
Observable characteristic, appearance (e.g. blue eyes).
Define genotype.
Combination of alleles and genes (e.g. GG).
Define locus.
Position/location of a gene on a chromosome/homologues.
Define allele.
Alternative versions of a gene.
What is a dominant allele?
Fully expressed in the heterozygote (capital letter).
What is a recessive allele?
Not observable in phenotype of heterozygote (lower case letter).
What is a heterozygous?
2 different alleles.
What is a homozygous?
Homozygous dominant: 2 same dominant alleles.
Homozygous recessive: 2 same recessive alleles.
What are the probable locations of eye colour alleles on chromosomes of Gg individuals in metaphase?
G and g must be on homologous chromosomes. 1 chromosome has G on each chromatid and 1 chromosome has g on each chromatid (because the 2 sister chromatids are identical).
