Unit 5 Flashcards
What is the difference between haploid and diploid cells?
Haploid cells contain only 1 set of chromosomes (n) and are formed by meiosis. Diploid cells contain 2 sets of chromosomes (2n) and are formed during mitosis.
Describe at least three different ways that genetic diversity is increased during gamete formation and reproduction.
Genetic diversity is increased during gamete formation and reproduction by independent assortment of chromosomes, crossing over, and random fertilization
Law of independent assortment
During meiosis, the pairs of homologous chromosomes are separated into different gametes independently of each other. This means each gamete receives a random mix of maternal and paternal chromosomes
Random fertilization
During sexual reproduction, the fusion of male and female gametes (sperm and egg) occurs randomly
What are homologous chromosomes?
pairs of homologuous chromosomes in a dioploid organism that have similar genes, although not necessasrily idential (sister chromatids)
Explain in detail what happens to the chromosome number during meiosis 1
Prophase 1: Chromosomes becomes visible and homologous chromosomes pair up and become tetrads.
Metaphase 1: Tetrads align in the center of the cell. Spindle fibers form and attach to the centromeres of homologous chromosomes.
Anaphase 1: Homologous chromosomes are pulled apart to opposite poles of the cell but the sister chromatids remain together.
Telophase 1: Cell divides into two haploid daughter cells.
Explain in detail what happens to the chromosome number during meiosis 2
Prophase 2: Chromosomes condense once again in each haploid daughter cell and new spindle fibers form
Metaphase 2: Chromosomes, still consisting of
What are the major similarities between mitosis and meiosis?
Similarities are they involve the division of a parent cell into daughter cell, replication of DNA during interphase, PMAT, and they involve the formation of a spindle apparatus.
What are the major differences between mitosis and meiosis?
Differences are their purpose, number of divisions, number of daughter cells, chromosome number, genetic variation, homologous chromosomes, phases, crossing over, and cell type produced
What is crossing over? When does it occur? What is the result?
Crossing over is the exchange of genetic material between homologous chromosomes. Crossing over occurs during Prophase I of meiosis. Crossing over results in genetic diversity, chromatic variation, and inheritance
Genetic diversity
The main outcome of crossing over is the creation of new combinations of alleles on each chromosome. This contributes to the genetic variation among offspring.
chromatid variation
After crossing over, sister chromatids are no longer identical. Each chromatid has a unique combination of alleles, leading to increased diversity in the gametes produced.
inheritance
This process ensures that each gamete (sperm or egg) carries a unique set of genetic information, which, when combined during fertilization, produces genetically diverse offspring.
Describe the major stages of the cell cycle.
The major stages of the cell cycle are interphase and M phase
Interphase
Interphase is the phase during which the cell grows, performs its normal functions, and prepares for division
G1 phase
The cell grows in size, synthesizes proteins, and produces organelles. At checkpoint, the cell assesses whether it has sufficient resources and proper conditions to proceed to the next phase
S phase
DNA replication occurs, resulting in the duplication of chromosomes. Each chromosome consists of two sister chromatids held together by a centromere. Results in the cell’s DNA content doubles, ensuring that each daughter cell will have an identical set of chromosomes.
G2 phase
The cell continues to grow and produce proteins necessary for mitosis. Organelles are duplicated, and the cell prepares for division. At checkpoint, the cell checks for DNA damage and ensures that all DNA has been accurately replicated.
M phase
the period during which the cell divides its nucleus and cytoplasm to form two daughter cells. It includes mitosis and cytokinesis
Law of segregation
states that each individual has two alleles for each gene, one from each parent, and that these alleles segregate (separate) during the formation of gametes (sperm or egg cells).
Law of Dominance
states that when two different alleles are present in an individual, one (the dominant allele) will mask the expression of the other (the recessive allele).
Explain how mitochondrial DNA does not follow meiotic inheritance patterns
Mitochondrial DNA is passed down maternally, does not undergo recombination, and is identical among siblings from the same mother.
Meiotic Inheritance Involves both parents’ nuclear DNA, includes recombination, and results in genetic diversity among offspring.
What is the expected ratio for a monohybrid cross
3 Dominant: 1 recessive
What is the expected ratio for a dihybrid cross
9: Dominant for both traits
3: Dominant for one trait
3: Dominant for the other trait
1: Recessive for both traits
What is the expected ratio for a Linked genes
1:1
What is the Chi squared formula?
(observed-expected)^2 /expected
How can a karyotype be used to diagnose chromosomal abnormalities?
It can be used to check numerical abnormalities, structural abnormalities, and sex-chromosome abnormalities
What is a karyotype?
A karyotype is an image or diagram showing the complete set of chromosomes of an organism, typically arranged in pairs by size, shape, and number.
Explain how the environment can affect a phenotype.
Environmental factors interact with genetic predispositions to shape the phenotype of an organism. This complex interplay ensures that individuals can adapt to their surroundings, enhancing their chances of survival and reproduction
What are some factors that result in environmental changes?
Nutritional factors, temperature, light exposure, chemical exposure, social environment, and epigenetics
What are the sex-chromosomes for males and females.
Females: XX
Males: XY
