Lecture 2

How many autosomes are in a human cell?

44 autosomes (22 pairs of two copies each).

What is the region between the +1 site for transcription and the start codon called?

The 5’ UTR.

What is the difference between an exon and an intron?

An exon is included in the RNA transcript, while an intron is spliced out.

Is the 5’UTR part of an exon or an intron?

It is part of the first exon.

What is added during the processing of a transcript?

The polyA tail and 5’ cap.

Where does translation start?

At the start codon on the mRNA.

What is the open reading frame?

It refers to the protein-coding sequences, everything that gets translated.

What percent of the human genome is part of an open reading frame?

3%.

Are there more protein coding genes or non-protein coding genes?

There are more non-protein coding genes.

What is the most common type of retrotransposon in the human genome?

ALU, which is a type of SINE.

What strategy does the genome employ to prevent retrotransposons from disrupting it?

The human genome is primarily maintained in a suppressive state.

Why does a pseudogene of a protein coding gene present an opportunity for evolution?

A pseudogene resembles a functional gene but does not encode for protein, allowing a new copy to evolve into a functional gene.

What are two big parts of human chromosomes made of repetitive elements?

Telomeres and satellite DNA at centromeres.

What is an acrocentric chromosome?

A chromosome where the P-arm is very short, often holding tandem arrays of ribosomal RNA genes.

Why is it necessary to have unique repetitive elements at the ends of chromosomes?

To prevent chromosomes from sticking to each other and to allow telomerase to prime replication.

What are the major differences between types of polymorphisms in the human genome?

The size of the polymorphism and whether a repeating unit is involved.

What are three practical uses for polymorphisms in the human genome?

Linkage analysis, DNA fingerprinting, and genome-wide association studies.

What is the difference between phenocopy and genetic heterogeneity?

Phenocopy refers to the same phenotype from different genetic causes, while genetic heterogeneity refers to the same mutation resulting in a range of phenotypes.

How do phenocopy and genetic heterogeneity disrupt linkage analysis?

They prevent mapping the trait to a single locus due to multiple mutant genes.

What is a TAD?

A topologically associated domain, a self-interacting genomic region.

How do TADs form?

Boundary elements bound by CTCF protein define TAD, allowing DNA loops to create separate compartments.