Lecture 10 - genes to traits Flashcards
what is a gene?
a gene is a basic unit of inheritance - the instruction for a trait which is passed on from generation to generation (i.e., heritable)
what is a trait?
a heritable physical characteristic i.e., pea shape, wrinkled or smooth, or a heritable physiological characteristic, i.e., ability to taste
what is the beadle and tatum experiment?
an experiment involving fungi autotroph that lead to the discovery of the one gene - one protein hypothesis. DNA polyermase is an example of this
what do we now know is more accurate of a description of the one gene one protein hypothesis?
one gene - one polypeptide.
what do we now know is more accurate of a description of the one gene one protein hypothesis?
one gene - one polypeptide.
how many base pairs are there in the human genome?
approx. 3 billion bp
how many genes are there in the human genome?
approx. 21000
how many genes are there in the human genome?
approx. 21000
what is the molecular anatomy of a gene?
two parts:
>coding region
>promotor (control region)
what is the molecular anatomy of a gene?
two parts:
>coding region
>promotor (control region)
what is the difference between the coding strand and the template strand?
> the coding strand contains the order of nucleotides that actually codes the polypeptide.
the template strand the the strand that is actually transcribed, i.e., it is the complementary sequence to the coding strand.
what is the difference between the coding strand and the template strand?
> the coding strand contains the order of nucleotides that actually codes the polypeptide.
the template strand the the strand that is actually transcribed, i.e., it is the complementary sequence to the coding strand.
what is chromatin made up of?
DNA plus histone proteins
what are the 8 levels of condensing of DNA?
1) chromatin is a double-stranded helical structure of DNA
2)DNA is complexed with histones to form nucleosomes.
3) each nucleosome consists of 8 histone proteins around which the DNA wraps 1.65 times.
> it keeps wrapping but they have cut the notes out lol
what are the 8 levels of condensing of DNA?
1) chromatin is a double-stranded helical structure of DNA
2)DNA is complexed with histones to form nucleosomes.
3) each nucleosome consists of 8 histone proteins around which the DNA wraps 1.65 times.
> it keeps wrapping but they have cut the notes out lol
how many types of histones are they are what are their names?
5 different types:
> H1 - (doesn’t actually form the octamer)
>H2A, H2B, H3 and H4.
>they are basic (alkaline, +ve charge) relatively small proteins that associate with the negatively charged phosphate-sugar backbone of DNA (electrostatic attraction)
what forms the octamer used in DNA condensing?
two of each of histones H2A, H2B, H3 and H4 proteins form a larger octamer which is at the core of a nucleosome.
what is a nucleosome?
a structure consisting of the histone octamer and 1.65 wraps of DNA molecule around it.
what structure on the nucleosome plays an important role in the transcriptional activity of the DNA?
the ends of the histone molecule which protrude onto the surface of the chromatin/DNA and can be chemically modified.
how does chromatin overcome the problem of being too condensed, making the DNA inaccessible?
it makes part of the chromosome accessible by relaxing the compaction level.
what are the two main types of chromatin?
> Euchromatin - relaxed, more easily transcribed, genes are most likely located here.
heterochromatin - compact, transcriptionally silent.
what are the two main types of chromatin?
> Euchromatin - relaxed, more easily transcribed, genes are most likely located here.
heterochromatin - compact, transcriptionally silent.
what is a locus?
> the address on the chromosome where genes are located.
>the information content of a gene is determined by the DNA sequence at a locus.
what is a locus?
> the address on the chromosome where genes are located.
>the information content of a gene is determined by the DNA sequence at a locus.
what are autosomes?
> the 22 paired chromosomes in the human genome.
> autosomes are of all different size, therefore unequal genetic content.
