Biology Chapter 3: Molecular Genetics Flashcards
Difference between eukaryotes and prokaryotes: RNA polymerase
Eukaryotes: have RNA polymerase I, II, II whereas prokaryotes just have RNA polymerase
3’ poly A tail purpose
Anti degradation in cytoplasm
Splicesomes are found in the
Nucleus
What is splicing
Non coding sequences are removed and coding sequences ligated
Does siRNA exert transcriptional control or post-transcriptional control
Post-transcriptional control.
siRNA can only bind to other RNA strands NOT DNA or protein
Therefore, it must interfere with gene expression after transcription has already occurred, but before translation. Specifically, it prevents the translation of mRNA corresponding to the target protein.
Viable trisomies
Trisomy 21, 18, and 13
Acrocentric chromosomes
have the centromere near one end, resulting in a very short p arm and a long q arm, often containing repetitive DNA and ribosomal RNA genes
Translocation
chromosomal abnormality where a segment of one chromosome is transferred to another chromosome
Cell differentiation is mediated primarily by:
gene expression levels.
Polygenic Inheritance
A trait is influenced by multiple genes (e.g., height, skin color).
Polymorphism
genes that have multiple alleles, or variant forms, in a population. These variations can occur in the DNA sequence and can affect the gene’s function.
ie there are more than 2 alleles in blood type that exist in more than 1% of the population (A,B,O)
Why is it 8% for males?
If the allele frequency is 8%, this means that 8% of men would be color blinded because they only need 1 Xc
Primase
generates an RNA primer, which does not contain DNA nucleotides, to match a fragment of DNA at the beginning of DNA replication.
A gene where only one allele is expressed, while the other allele is silenced based on its parental origin. This means that whether the maternal or paternal allele is active depends on imprinting marks (epigenetic modifications like DNA methylation and histone modifications).
imprinted gene
Why Does Xi Replicate Late?
Xi still replicates, just later than the active X
Why is it late?
Heterochromatin Structure: The Xi is tightly packed, making it less accessible to replication machinery.
Reduced Transcriptional Activity: Since it’s mostly inactive, it is not prioritized for early replication.
Cellular Energy Conservation: Cells prioritize active genes and euchromatin for early replication to ensure proper gene expression.
Amber codons
An amber codon is a stop codon.
The discovery that the amount of thymine equals that of adenine and the amount of guanine equals that of cytosine in a given cell provides supporting evidence that:
The Watson Crick Model of DNA
In the Watson and Crick model of DNA structure, the nitrogenous bases form hydrogen bonds with each other in a 1:1 ratio: guanine pairs with cytosine, and adenine pairs with thymine. This implies that the amount of guanine and cytosine would be the same, and the amount of adenine and thymine would be the same.
Explain why it’s D
❌ I because genes are highly conservative - meaning their sequences and functions have stayed the same across species through evolution.
✅ II humans could have an immune response to virus delivery
✅ III how do you target the full tumour??
