1 Human Genome Flashcards
what is a locus?
physical position of a gene in a chromosome
what is dossage?
number of copies of a given gene in the genome
like in down sd more than 2 copies
or turner just one copy
what is allele
alternative form or alternative copy of a gene in a given locus
where do we get each allele from?”
one from mom and one from dad
- homozygous (2 copies of same allele)
- heterozygous (2 differetn copies
how many base pair on a:
- kb
- Mb
- cM
- kb 1000 bp
- Mb 1 million bp
- cM (centermorgan) ~1% recombination = 1MB
what is the genetic size in cM?
for females
for males
and the average
why females more than males?
- females 4400 cM
- males 2700 cM
- sex-averaged 3700 cM
females more due to increased recombination
how many base pairs do we have in the human genome?
- 6 x 109 diploid
- 3 x 109 haploid
what is splicing?
its the editing of RNA
removing introns
and putting the exons together
is it correct to say ONE gene encodes for ONE PROTEIN?
NO… that is a very old concept.
ONE GENE can make multiple different proteins or products
For this reason, we used to say that there were 100K protein-coding genes but now we say there are 20K protein-coding genes
This is explained due to ALTERNATIVE SPLICING
what is the average size of protein-coding genes?
- 14Kb
- (range 2-2400 kb)
- there are ~10 exons/gene
what is the average # of exons per gene?
~10 exons/gene
what % of genes produce more than one mRNA (and thus, more than once protein)
60%
which one of the biggest genes?
the dystrophin gene
DNA strands are parallel or anti-parallel?
anti-parallel
what sugars are in DNA and RNA?
DNA dexosiribose
RNA ribose
which are the TWO purines and the
THREE pirimidines?
- Purines: A-G
- A adenine
- G guasnine
- Pyrimidines TUC
- C cytosine
- T Thymine
- U uracil
what are the pairs for ATCGU? foe each
- A with T
- C with G
what is DNA replication and how fast it happens?
its the DNA reproduction from 1 DNA to TWO daughters DNA
- speed of 40 nucleotides/sec i eukaryotes
what is the DNA replicatio direction?
- 5’ to 3’ leading strand
- the other strand LAGGING STRAND is 3’ to 5’ is synthesized in pieces (okasaki fragments)
what is translation and what is transcription?
- DNA to RNA is TRANSCRIPTION
- RNA into protein is TRANSLATION
- remember the sequence is DNA to RNA to protein
- remember your FIRST TRANSCRIBE
- translators for next, translators need the paper written instructions.
is it OK to say that genes code for proteins?
that is an old concept…
Genes code for FUNCTIONAL PRODUCTS
what is ncRNA gene and how many
non-coding RNA genes
and there are the same number of coding genes so around 20K
the difference is that ncRNA genes are very small
what is the gene structure?
- Promoter (5’ info to start)
- UTR untranscripted region
- Exons
- introns
- termination codon
- 3’ region
what is the RNA difference in structure to DNA?
RNA has:
- ribose
- single stranded
- Uracil replaces thymine
synthesis of primary RNA occurs in which direction?
5’ to 3’
which are achrocentric chromosomes?
13, 14, 15, 21, 22
what is a robertsonian translocation
- rare form of chromosomal rearrangement
- occurs only in the 5 achrocacrocentricosomes
- these are 13, 14, 15, 21, 22
- its when 2 of these join together (by the q arms - no p arms)
- most babies with robertsonian translocation (RT) have parents with normal chromosomes
- some babies have one parent with a RT (carrier)
- two types
- balanced rob = healthy, carrier
- unbalanced = chromosomal disorder
- ex: Down’s syndrome
- trisomy 13
- Prader willi
- Angelman
what is Transcription and translation order?
transcription 5’ to 3’
Translation 3’ to 5’
During transcription, which strand is transcribed?
The lower strand
Synthesis of RNA in transcription occurs in which direction?
5’ to 3’
Name some polymerases and what is their function?
- Pol I
- Transcribe rRNAs
- Pol II
- mRNA
- microRNAs
- Pol III
- tRNA
- Pol G
- Mitochondrial
To help in the splicing process there are 2 types on enhancers
- ESE exon splicing enhancers
- ISE intron splicing enhancers
- They bind serine rich proteins and other factors to select splice sites
- They tell where is the splicing
What is translation? Where does it occur
- RNA to protein synthesis
- Goes 3’ to 5’
- Occurs in ribosomes
What is a codon?
Set of 3 bases that specify an AA
What is the codon that initiates TRANSLATION?
ATG - Methionine (almost always) if embedded in Kozak
How many AA have one codon? Meaning that only one codon combination forms them
TWO
- Methionine AUG or AGG
- Tryptophan UGG
Which are the termination codons?
UAA, UAG, UGA
Why do we say genetic code is degenerate?
Because most AA are specified by more than one codon
Changing the 1st base sometime changes the AA
Changing the 2nd base ALWAYS changes the AA
Changing the 3rd sometimes
Which are the stop codons?
- UGA
- UAG
- UAA
What are the steps in translation?
- Initiation
- Methionine until AUG
- Elongation
- tRNA binds to A-site
- Termination
How many million bases in one CentiMorgan?
1 million bp on one Centimorgan
Alternative transcription
- In dystrophin protein for example
- Similar to alternative splicing
What is mRNA?
Messenger RNA
Characteristics of tRNA?
- Cloverleaf pattern
- Together by hydrogen bonds
What are the ribosome sites?
P & A sites