DNA and Meiosis Flashcards
What happens during metaphase I?
Homologous chromosomes line up in PAIRS in the middle of the cell.
What is a haploid cell? What is the haploid number in humans? Give an example.
- A haploid cell is a cell with one set of chromosomes
- 23
- Sperm and egg
What is the biggest difference between spermatogenesis and oogenesis?
In spermatogenesis 4 haploid cells form; only 1 mature egg forms in oogenesis (cytoplasm is unequally divided)
What is spermatogenesis? How many haploid cells form?
-Sperm production in males
-4 haploids from one diploid
What is a monomer of DNA?
A nucleotide
What is a monosomy?
The loss of a chromosome as a result of nondisjunction
What stage is this?
Anaphase II
What stage is this?
Metaphase II
What is the female karyotype?
XX
What stage is this?
Telophase II
What are the nitrogenous bases?
(Write out spelling)
- Adenine
- Thymine
- Guanine
- Cytosine
What happens during prophase I?
(Hint: 4 things)
- Homologous chromosomes condense
- Crossing over occurs
- Nuclear membrane breaks down
- Spindle fibres attach
What stage is this?
Telophase I
What happens during anaphase II?
-Chromosomes split at the centromere
-Sister chromatids move to opposite ends of the cell
What do the order of nitrogenous bases determine?
Genectic sequence/DNA sequence
What stage is this?
Prophase I
What are purines? What are they?
- Two ringed bases
- Adenine and Guanine
What happens during telophase II?
-Nuclei form around chromatids
-Spindle fibres break down
What happens during crossing over?
Exchange of segments of chromosomes that occur between a pair of homologous chromosomes.
What is a tetrad? What is an autosome?
- A pair of homologous chromosomes
- A NON-SEX chromome
What are the two outcomes of meiosis?
Describe them.
Genetic reduction: Produces daughter cells with half the number of chromosomes of parents cells. (End product: 4 daughter cells)
Genetic Recombination: Products of meiosis have different combinations of alleles.
What are pyrimidines? What are they?
- One ringed bases
- Thymine and Cytosine
What are the remaining 3 haploid cells in oogenesis called? What is their function?
-Polar bodies
-Help with fertilization
What is the male karyotype?
XY
What stage is this?
Metaphase I
What is a trisomy?
Gain of an extra chromosome as a result of nondisjunction
What are the 4 errors in structure during meiosis? Describe them.
Deletion: A piece of a chromosome is deleted
Duplication: A section of a chromosome appears two or more times
Inversion: A section of a chromosome becomes inverted (ATTAG - GATTA)
Translocation: A large section of a chromosome attaches to another
What is the structure of DNA?
- Double Helix Shape
- Pentose Sugar and phosphate (sides of the ladder)
- Nitrogenous bases link with hydrogen bonds (steps of the ladder)
What stage is this?
Prophase II
What happens during anaphase I?
Homologous chromosomes are separated and pulled to opposite sides of the cell.
What happens during telophase I?
(Hint: 3 things)
-Spindle fibres break down
-Nuclear membrane begins to form around two nuclei
-Cytokinesis occurs and the cell separates into two daughter cells
Define nondisjunction:
The failure of homologous chromosome pairs or sister chromatids to separate during meiosis
What is a diploid cell? What is a diploid number in humans? Give an example.
- A diploid cell is a cell with two sets of chromosomes
- 46
- Body cells
What stage is this?
Anaphase I
What happens during metaphase II?
Individual chromosomes line up in the middle of the cell
What is oogenesis? How many haploid cells form?
-Egg production in females
-1 MATURE EGG forms from one diploid
What do nucleotide consist of?
- A phosphate group
- 5 carbon sugar
- Nitrogenous bases
What is Chargaff’s rule?
Adenine binds with thymine (A+T)
Guanine binds with cytosine (G + C)
What happens during prophase II?
Chromatin tighten and spindle fibres attach to chromosomes
What is a homologous chromosome? Give an example.
One pair of chromosomes that share similar characteristics; one from each parent.
(Example: Similar length, similar centromere location, same genes in same spots)
Compare and contrast mitosis vs meiosis
Answer on paper
