L9 MEIOSIS Flashcards
What is the genetic makeup of asexual offspring?
They are identical copies of parents, have identical DNA copies.
What is the genetic makeup of sexual offspring?
Their genes are a unique combination of maternal and paternal genes.
What is a somatic cell?
A non-sex cell
How many chromosomes do somatic cells have?
46 chromosomes, or 23 pairs of chromosomes.
How may chromosomes do gametes have?
23 chromosomes, no pairs.
TRUE OR FALSE: the daughter cells produced in meiosis are exact copies of parental cells.
FALSE: in mitosis, daghter cells are copies. In meiosis, daughter cells have unique genes.
What is an autosome?
A non-sex chromosome.
Fill in the blanks.
CHROMOSOME consisting of one CHROMATID.
Both chromosomes are SISTER CHROMATIDS.
On the right is a DUPLICATED CHROMOSOME
The middle of the chromosome is the CENTROMERE.
Fill in the blanks.
PROPHASE I:
The REPLICATED chromosomes condense. Homologous chromosomes come together in SYNAPSIS and CROSSING-OVER occurs. Chromosomes attach to the SPINDLE.
Duplicated/replicated chromosomes are NOT the same as homologous chromo.
The replication of the chromosome happened in interphase.
Fill in the blank.
METAPHASE I:
TETRADS like up at the METAPHASE plate.
Spindles also attach to kinetochores.
Fill in the blanks.
ANAPHASE I:
Each CHROMOSOME separates from its TETRAD. They move to OPPOSITE POLES OF THE CELL.
goes from 2N > N
Fill in the blanks.
TELOPHASE I:
The nucleus completes division. The CHROMOSOMES are still composed of SISTER CHROMATIDS.
These sister chromatids are no longer identical due to crossover.
Fill in the blanks.
PROPHASE II:
The CENTRIOLES in the two new cells move to opposite poles and new SPINDLE FIBRES form. The CHROMOSOMES become attached to the SPINDLE.
Fill in blanks.
METAPHASE II:
CHROMOSOMES line up at the METAPHASE plate.
Fill in the blanks.
ANAPHASE II:
RECOMBINED/SISTER CHROMATIDS of each chromosome separate and move to OPPOSITE POLLS.
Fill in the blanks.
TELOPHASE II:
The cytoplasm separates, leaving FOUR HAPLOID DAUGHTER cells. The CHROMOSOME number has been reduced by half.
When does chromosome replication occur?
During Interphase before the meiosis.
Whay is synapsis?
Synapsis is the process where homologous chromosomes come together to form tetrad and are held together by proteins.
What is Chiasma?
Chiasma is the physical manifestation of crossing over.
What is the main goal of Meiosis II?
To separate the sister chromatids, and distribute each copy of each chromosome into a new cell.
What three mechanisms contribute to genetic variation in meiosis?
- Independent assortment of chromosomes.
- Crossing over.
- Random fertilization.
What are the names for the processed of male and female gamete cells going through meiosis?
Spermatogenesis and Oogenesis.
Why is independent assortment of chromosomes important?
The randion orientation of chromosomes at metaphase I allow for millions of possible chromosome combination = extreme diversity.
What is a recombinant chromosome?
The result of crossing over, where a chromosome has been recombined with new genes. # of genes stays the same, but alleles may differ.
