Mitosis and Meiosis
Which stage of mitosis is described as "chromosomes become visible"?
What is Prophase?
Which mutation type is a change in a single nucleotide? (Give the named term.)
What is Point mutation?
What is the term for DNA wrapped around proteins that codes for several genes?
What is Chromosome?
What is crossing over?
Crossing over is when a segment of a chromatid breaks off and reattaches to a different chromatid, exchanging genetic material.
In what stage does DNA replicate before cell division begins?
What is Interphase (S phase)?
What is a substitution?
A substitution is when one nucleotide is replaced by a different nucleotide.
What is a chromatid?
Chromatid is one of the two threadlike strands into which a chromosome divides during cell division.
During which meiotic stage does crossing over primarily occur?
What is Prophase I of meiosis?
Put these mitosis stages in correct order: Anaphase, Prophase, Telophase, Metaphase, Cytokinesis.
What is Prophase →Metaphase → Anaphase → Telophase → Cytokinesis?
Define insertion and deletion at the nucleotide level (one sentence each).
What is Insertion: an extra nucleotide is added; Deletion: a nucleotide is removed?
What name is given to the constricted part of a chromosome that holds sister chromatids together?
What is Centromere?
Define nondisjunction.
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly
During which meiotic phase do homologous chromosomes pair and form tetrads?
What is Prophase I (meiosis I)?
What is a point mutation and how can it affect a protein?
A point mutation is a single-nucleotide change; it can change an amino acid in a protein or be silent if it doesn't alter the amino acid
Where do spindle fibers attach on chromatids? (Use the technical term.)
What is Kinetochore?
Describe one example (name a disorder) that can result from nondisjunction in humans
What is Down syndrome (Trisomy 21)?
Compare the outcomes: How many daughter cells and with what chromosome number result from mitosis versus meiosis? (One clear sentence.)
Mitosis produces two genetically identical diploid daughter cells; meiosis produces four genetically unique haploid gametes?
Explain how a frameshift mutation can result from insertion or deletion and why it often has larger effects than a substitution.
Frameshift mutations shift the reading frame when insertions or deletions are not in multiples of three, altering every downstream codon and usually severely changing the protein.
What is a tetrad?
A tetrad is two homologous chromosomes paired together (during meiosis I), comprising 4 chromatids total (2 chromatids per chromosome).
Explain how crossing over between non-sister chromatids can produce recombinant chromosomes and how that contributes to genetic diversity
Crossing over between non-sister chromatids swaps allele segments, creating recombinant chromosomes that carry new allele combinations; these recombinants increase genetic diversity among offspring because gametes carry novel allele assortments.