Mitosis
In which phase of mitosis do the chromosomes first become visible?
a) Prometaphase
b) Metaphase
c) Anaphase
d) Telophase
a) Prometaphase
Humans are diploid organisms. What does this mean?
A) Humans have one set of chromosomes, inherited from both parents.
B) Humans have two sets of chromosomes, one inherited from each parent.
C) Humans have two copies of every chromosome, but only one set of chromosomes.
D) Humans have three sets of chromosomes, one inherited from each grandparent.
B) Humans have two sets of chromosomes, one inherited from each parent.
1) Where does transcription occur in a prokaryotic cell?
2) Where does transcription occur in a eukaryotic cell?
1) Cytoplasm
2) Nucleus
1) Where does translation occur in a prokaryotic cell?
2) Where does translation occur in a eukaryotic cell?
1) Cytoplasm
2) Cytoplasm
1) What is a gene?
2) What is an allele?
1) A gene is a segment of DNA that codes for a specific protein or trait; "eye color"
2) An allele is a variation of a gene; "green eyes" or "blue eyes"
How does the process of mitosis differ in plant cells compared to animal cells?
In plant cells, during cytokinesis, a cell plate forms and eventually becomes a new cell wall, dividing the daughter cells. In animal cells, a cleavage furrow forms, pinching the membrane to separate the daughter cells.
What are the differences between somatic cells and gametes?
Somatic cells are the cells NOT utilized for reproduction (the creation of a zygote). For example: skin cells, muscle cells, hair cells, etc.
Gametes are the cells directly utilized for reproduction (the creation of a zygote). This includes a sperm cell that comes together with an oocyte to create a zygote.
The mRNA strand will always run in the ___ to ___ direction; therefore, the DNA template strand will always run in the ___ to ___ direction.
5' to 3'
3' to 5'
Which of the following statements best describes the function of aminoacyl-tRNA synthetase in protein synthesis?
A) It catalyzes the binding of an amino acid to its corresponding tRNA molecule.
B) It catalyzes the formation of peptide bonds between amino acids during translation.
C) It decodes mRNA codons into their corresponding amino acids.
D) It synthesizes mRNA from a DNA template during transcription.
A) It catalyzes the binding of an amino acid to its corresponding tRNA molecule.
What is the difference between homozygous and heterozygous?
Homozygous means having two identical alleles for a gene, while heterozygous means having two different alleles for a gene.
Define the following "C" words
1) Chromosome
2) (Sister) Chromatids
3) Centromere
4) Centrosome
5) Chromatin
6) Kinetochore
1) One condensed DNA molecule
2) Two duplicated, identical DNA molecules; after S-phase
3) Region of attachment of sister chromatids
4) Organelle that organizes & sprouts microtubules
5) Uncondensed DNA
6) Protein found on centromere where microtubules directly attach to
What are the three main sources of genetic variation in organisms?
1) Independent Assortment: Homologous chromosomes line up in a random order during Metaphase I in Meiosis.
2) Recombination of nonsister chromatids: During meiosis I, nonsister chromatids exchange pieces of DNA, creating new gene combinations.
3) Fertilization: one RANDOM sperm cell and one RANDOM oocyte come together
The promoter and transcription factors are essential for transcription of gene expression to begin. What do they do?
A promoter is a region of DNA that signals the start of a gene (contains the "TATA BOX")- it is the binding site for RNA polymerase to begin transcription. The transcription factors physically help recruit and stabilize RNA polymerase at the promoter site.
Explain the interaction between the codon and anticodon. Where does this interaction occur, and why is it crucial for protein synthesis?
The codon-anticodon interaction occurs in the ribosome's A site, where the mRNA codon pairs with the complementary tRNA anticodon to ensure the correct amino acid is added during protein synthesis.
Albinism is caused by a recessive allele (a), while the allele for normal pigmentation is completely dominant (A). A man with normal pigmentation who is heterozygous (Aa) marries a woman who is also a carrier for albinism (Aa). What are the possible genotypes/phenotypes of their offspring?
Genotype:
Phenotype
How does the mitotic spindle ensure proper chromosome alignment and separation during mitosis?
The mitotic spindle consists of microtubules (sprouting from centrosomes) that attach to the centromeres of chromosomes via kinetochores. These microtubules "pull" the chromosomes towards the poles of the cell during anaphase, ensuring that each daughter cell receives an identical set of chromosomes!
1) What is the difference between Prophase I of Meiosis and Prophase of Mitosis?
2) What is the difference between Anaphase I of Meiosis and Anaphase of Mitosis?
1) Prophase I of Meiosis is where synapsis, crossing over, and recombination of nonsister chromatids occurs (they exchange genes *for diversity purposes*)
2) Anaphase I of Meiosis separates homologous chromosomes; while Anaphase of Mitosis separates sister chromatids.
What is the difference between pre-mRNA and mRNA? (Which cells do we see these structures in?)
Pre-mRNA is only seen in Eukaryotic cells. It consists of introns AND exons.
mRNA is seen in both types of cells. It consists of ONLY exons and also contains modified ends (5' cap and 3' PolyA-tail).
What is the "shifting frame" mutation in translation, and how does it impact protein synthesis?
A frameshift mutation occurs when nucleotides are inserted or deleted in a way that shifts the reading frame of the mRNA. This causes the ribosome to read the codons incorrectly, often resulting in a nonfunctional protein. These mutations can be particularly damaging because they change the entire amino acid sequence downstream of the mutation.
In order for a daughter to inherit X-linked colorblindness, which of the following must be true about her parents?
A) The father must be colorblind, and the mother must be a carrier or colorblind.
B) The mother must be colorblind, and the father must have normal vision.
C) Either parent can be colorblind for the trait to be passed on.
D) The mother must be colorblind, and the father must be colorblind.
A) The father must be colorblind, and the mother must be a carrier or colorblind.
Describe the role of cyclins and cyclin-dependent kinases (CDKs) in regulating the cell cycle.
Cyclins are regulatory proteins that bind to CDKs, forming MPF. A high [] of MPF allows progression through the checkpoints (e.g., G1/S, G2/M). Without proper cyclin-CDK regulation, the cell cycle can become uncontrolled, leading to cancer.
** MAIN POINT: When cyclin [] rises, the [] of MPF also rises, and it signals the cell that it is ready to move onto the next phase of the cell cycle.
What are the key differences between Meiosis and Mitosis? Answer:
1) What do we produce at the end of these processes?
2) What steps are seen in these processes?
3) Where do these processes occur?
1) Meiosis produces four non-identical, haploid (1n) daughter cells, while mitosis produces two identical, diploid (2n) daughter cells.
2)Meiosis involves two rounds of PMAT (Prophase, Metaphase, Anaphase, Telophase), whereas mitosis only involves one round of PMAT
3) Meiosis occurs only in reproductive cells (gametes), while mitosis is responsible for the division of somatic (non-reproductive) cells.
How does Transcription differ in Eukaryotic vs. Prokaryotic cells?
In Eukaryotic cells, the end product of Transcription is pre-mRNA. So therefore, RNA processing is required after Transcription.
In Prokaryotic cells, the end product of Transcription is mRNA. So therefore, RNA Processing is not required.
How does Translation differ in Eukaryotic cells vs. Prokaryotic cells?
In Eukaryotic cells: Translation happens in the cytoplasm at free ribosomes. If the protein has a signal peptide, the ribosome attaches to the rough ER, becoming a bound ribosome. Translation occurs only after transcription and RNA processing are completed.
In prokaryotic cells: Translation also happens in the cytoplasm, but it occurs simultaneously with transcription. Because this process is faster, multiple ribosomes (polyribosomes) can work on the same mRNA at once.
Explain the difference between complete dominance and codominance with examples.
In complete dominance, the heterozygous phenotype shows the dominant allele expressed and the recessive allele is "masked/hidden" (e.g., a plant with one purple allele (P) and one white allele (p) will have purple flowers).
In codominance, the heterozygous phenotype shows both dominant alleles equally expressed (e.g., a person with one A allele and one B allele has AB blood type).