RNA synthesis Flashcards
Define Transcription (1)
synthesis of mRNA transcript from DNA, same language – nucleic acid.
Define Translation (1)
protein production from mRNA transcript, different languages – nucleic acid to protein
How many nucleotides are there? (1)
3.2 x10^9
How many pairs of chromosomes have we got, and what are the two types? (3)
23 chromosomes- Autosomes 22 pairs and 1 pair of sex chromosomes
Define Autosomal linkage
Genes present on the same non-sex chromosomes.
Define sex-linked genes
Genes carried on the same sex chromosomes.
Purpose of a chromosome?
Chromosomes serve the purpose of carrying genes
What is the function of the centromere?
keeping chromosomes attached to the mitotic spindle during mitosis so that each new daughter cell has one copy.
Describe Telomeres
Located at the end of chromosomes.
Very relative DNA, 6 base pair repeats, protect the end of the chromosome ensuing genetic code is not destroyed or lost.
Prevents against strands linkages so that chromosomes don’t join together.
Describe Genes on a chromosome
20,000 genes
Gene – unit of heredity, contains instructions for an organism’s phenotype. DNA segment containing instructions for making a particular product, including the regulatory elements. It is not just a gene that codes for protein.
Intergenic region (between the genes) is composed of most of the DNA we carry, not much DNA is coding for proteins. They control how genes are expressed in a cell – we only just beginning to understand what they are.
An arrow on the length of a gene always represents where transcription starts.
What is an exon?
regions of coding DNA or RNA. Exons are expressed.
What is an intron?
regions of non-coding DNA or RNA.
What is the purpose of the 5’ and 3’ UTRS?
5’ - Regulation of translation
3’ - mRNA stability and miRNA binding
What are the different human RNA polymerases?
Type of polymerase Genes transcribed
RNA polymerase 1 Most ribosomal RNA (rRNA)
RNA polymerase 2 Protein-coding, microRNA (miRNA), non-coding RNA
RNA polymerase 3 Transfer RNA (tRNA), 5S rRNA, other small RNAs.
RNA synthesis
Dozens of polymerases work on the same gene
Many transcripts are produced from the same gene
Relatively quick 1.25-1.74kb (kilobase) per minute.
Transcription factors
Proteins required to initiate and regulate transcription in eukaryotes.
Assemble on the promotor region to help RNA polymerase 2 to bind.
They also pull apart DNA helix and expose template strand.
Why cap and polyadenylate?
- Stability
- Transport out of the nucleus
- Integrity prior to translation
Define Homologous chromosomes
chromosome pairs (one from each parent) that are similar in length, gene position, and centromere location. The position of the genes on each homologous chromosome is the same, however, the genes may contain different alleles. Paternal homolog is inherited from the father and maternal homolog is inherited from the mother
How is RNA exported from the nucleus
SPECIFIC ADAPTOR PROTEINS
POLY A BINDING FACTOR
EXON JUNCTION COMPLEX
CAP BINDING PROTEIN
Describe gene-specific regulation of transcription
There are additional sequences upstream needed for gene-specific regulation of transcription (e.g enhancers and proximal control elements.)
