Cell Division
What are the five phases of Mitosis?
Prophase, Metaphase, Anaphase and Telophase, and Cytokinesis
What is gene linkage?
Genes located close together on the same chromosome that tend to be inherited together.
What is semi-conservative replication?
A process where a DNA molecule is duplicated, and each newly formed double helix contains one original strand and one newly synthesized strand (Meselson and Stahl experiment)
What is the bacterial core promoter?
A region of a gene contains the -10 and -35 consensus sequences and is recognized by the RNA polymerase in bacteria.
What is positive regulation?
This type of regulation involves an activator protein increasing gene expression by facilitating RNA polymerase binding to the promoter
How to do new cells get their genetic diversity in meiosis?
What is purpose of complementation?
The purpose of complementation is to determine restore a wild type phenotype by crossing when organisms with each mutation are crossed, indicating that each provides the functional gene the other lacks
The leading strand is synthesized continuously in the 5′ to 3′ direction toward the replication fork
The lagging strand is synthesized discontinuously in short Okazaki fragments away from the fork, due to the antiparallel nature of DNA
What is alternative splicing?
A complex eukaryotic process modifies pre-mRNA by removing introns and joining exons, often regulated to produce multiple proteins from one gene.
What is mRNA turnover?
This process involves the controlled degradation of mRNA molecules, influencing how long they are available for translation
Name 3 major cell cycle checkpoints and the proteins involved
1) G1/S
2) G2/M
3) Spindle Assembly Checkpoint
Proteins: Cyclins and Cyclin-dependent kinases (CKDs)
What are 5 genetic phenomenon based on extension of Mendelian Genetics
1) Incomplete dom.
2) Codominance
3) Multiple alleles
4) Epistasis
5) Lethal dom/rec
6) Incomplete penetrance
7) Expressivity
What are key enzymes involved in DNA Replication? (5)
1) Helicase
2) Topoisomerase
3) Primase
4) DNA Polymerase I and III
5) Ligase
What is the role of initiator tRNA?
Initiator tRNA plays a crucial role in the initiation of protein synthesis by specifically recognizing and binding to the start codon (AUG) on mRNA
Why is the lac operon considered an example of both negative and positive regulation?
The lac operon is negatively regulated by the lac repressor, which binds the operator and blocks transcription in the absence of lactose. It's also positively regulated by the CAP-cAMP complex, which enhances RNA polymerase binding when glucose is low
What are some differences between Mitosis vs Meiosis?
1) Number of Divisions
2) Different Daughter Cells Produced
3) Function
4) Where it Occurs
How does the presence of a lethal allele change expected Mendelian ratios?
It causes certain genotypes to be nonviable, often resulting in a 2:1 instead of a 3:1 phenotypic ratio.
Why does DNA sequencing with Sanger's method use dideoxynucleotides (ddNTPs), and what happens when they are incorporated into the growing DNA strand?
Dideoxynucleotides lack the 3′-OH group required for the formation of the phosphodiester bond, causing termination of the DNA chain whenever they are incorporated. This allows the sequencing reaction to produce DNA fragments of varying lengths, which can then be read to determine the original DNA sequence.
1) How is the peptide bond formed between amino acids
2) How does the ribosome move along the mRNA during elongation?
1) The ribosome’s P site catalyzes the peptide bond between the amino group of the A-site amino acid and the carboxyl group of the P-site peptide.
2) Translocation occurs with help from elongation factors (EF-G or eEF2) and GTP hydrolysis, shifting the ribosome one codon forward.
Why does the lac operon remain off when both glucose and lactose are present?
When glucose is present, cAMP levels remain low, preventing formation of the CAP-cAMP complex. Without this activator, RNA polymerase cannot efficiently initiate transcription, so even if the repressor is inactive (due to lactose/allolactose), transcription remains minimal
A diploid cell from a human contains 16 chromosomes and 16 DNA molecules. How many chromosomes per cell are present in:
1) Prophase I
2) Metaphase II
3) Telophase II
1) Prophase I - 16 chromosomes, 32 DNA
2) Metaphase II - 8 chromosomes, 16 DNA
3) Telophase II - 8 chromosomes, 8 DNA
How do multiple alleles influence inheritance patterns in a population?
They increase genetic diversity and allow for more possible genotype and phenotype combinations
Summarize the Cloning Process (7 steps) and why we do it
1) Isolate DNA of interest
2) Cut DNA and plasmid with the same restriction enzyme
3) Mix the DNA insert with the plasmid vector
4) Add DNA ligase
5) Introduce recombinant plasmid into host bacteria cells
6) Grow cells on selective medium
7) Screen for successful clones
(techniques like blue-white screening or PCR)
WHY: Cloning is important because it allows scientists to replicate specific DNA sequences for studying gene function, personalized medicine, etc.
Why is the genetic code described as "degenerate," and what is the advantage of this degeneracy?
The genetic code is degenerate, meaning that multiple codons can specify the same amino acid. This provides a level of protection against mutations, as changes in the DNA sequence do not always alter the resulting protein.
How does chromatin structure influence gene expression in eukaryotes?
Tightly packed heterochromatin limits access of transcription machinery to DNA, repressing gene expression (HDAC process). In contrast, euchromatin is loosely packed, making promoter regions more accessible (HAT process).