lecture 2 - normal genome Flashcards
What is the human genome comprised of?
The human genome is comprised of 3.2 billion base pairs of DNA.
How is DNA packaged in the nucleus?
DNA is wound around histones to form nucleosomes, which are further packaged into chromatin fibers, then into loops, and ultimately into chromosomes.
How many pairs of chromosomes do humans have?
Humans have 23 pairs of chromosomes: 22 pairs of autosomes and 1 pair of sex chromosomes (XX for females, XY for males).
What are histones, and how do they regulate chromatin structure?
Histones are proteins around which DNA is wound. They can be post-translationally modified to regulate chromatin structure.
what is a gene?
a gene is a unit of DNA that encodes an RNA or protein product
What enzyme transcribes protein-coding genes?
RNA polymerase II transcribes protein-coding genes.
In which direction is the nucleotide chain synthesised during RNA transcription?
The nucleotide chain is synthesized in the 5’ → 3’ direction.
Are genes equally distributed across all chromosomes?
No. Some chromosomes are more gene-dense than others.
What is the approximate number of protein-coding genes in the human genome?
The human genome contains around 20,338 protein-coding genes.
What percentage of the genome undergoes alternative splicing?
Around 95% of multiexon genes undergo alternative splicing.
What are the three stages of translation?
Initiation, Elongation, and Termination.
What is the function of the A site in the ribosome?
The A site binds to tRNA carrying an amino acid during translation.
True or False: Genes are only found on the forward strand of DNA.
False. Genes can be found on both strands of DNA.
True or False: Genes can overlap on chromosomes.
True. Genes can be arranged in the same or opposite directions on a chromosome.
What is the proportion of the human genome that encodes proteins?
1-2% of the genome encodes proteins.
What are some types of functional non-coding RNA?
tRNA, rRNA, snRNA (small nuclear RNA).
What are some types of regulatory non-coding RNA?
miRNA, piRNA, snoRNA, lncRNA.
What is the difference between conventional and processed pseudogenes?
Conventional pseudogenes are non-functional gene copies with mutations, while processed pseudogenes arise from reverse transcription of mRNA.
How much of the human genome is transcribed into RNA?
About 90% of the genome is transcribed into RNA at some point.
What are repetitive DNA elements, and why are they important?
Repetitive elements play structural roles in centromeres, telomeres, and DNA looping.
What is the size and gene content of the human mitochondrial genome?
The mitochondrial genome is 16,569 bp long and contains 37 genes (13 protein-coding, 24 non-coding RNA genes).
What is the key takeaway about the human genome?
The genome is highly complex, well-organized, and primarily transcribes RNA rather than proteins.
