Lecture 10 - genes to traits

Question 1

what is a gene?

Answer 1

a gene is a basic unit of inheritance - the instruction for a trait which is passed on from generation to generation (i.e., heritable)

Question 2

what is a trait?

Answer 2

a heritable physical characteristic i.e., pea shape, wrinkled or smooth, or a heritable physiological characteristic, i.e., ability to taste

Question 3

what is the beadle and tatum experiment?

Answer 3

an experiment involving fungi autotroph that lead to the discovery of the one gene - one protein hypothesis. DNA polyermase is an example of this

Question 4

what do we now know is more accurate of a description of the one gene one protein hypothesis?

Answer 4

one gene - one polypeptide.

Question 5

what do we now know is more accurate of a description of the one gene one protein hypothesis?

Answer 5

one gene - one polypeptide.

Question 6

how many base pairs are there in the human genome?

Answer 6

approx. 3 billion bp

Question 7

how many genes are there in the human genome?

Answer 7

approx. 21000

Question 8

how many genes are there in the human genome?

Answer 8

approx. 21000

Question 9

what is the molecular anatomy of a gene?

Answer 9

two parts:
>coding region
>promotor (control region)

Question 10

what is the molecular anatomy of a gene?

Answer 10

two parts:
>coding region
>promotor (control region)

Question 11

what is the difference between the coding strand and the template strand?

Answer 11

> 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.

Question 12

what is the difference between the coding strand and the template strand?

Answer 12

> 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.

Question 13

what is chromatin made up of?

Answer 13

DNA plus histone proteins

Question 14

what are the 8 levels of condensing of DNA?

Answer 14

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

Question 15

what are the 8 levels of condensing of DNA?

Answer 15

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

Question 16

how many types of histones are they are what are their names?

Answer 16

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)

Question 17

what forms the octamer used in DNA condensing?

Answer 17

two of each of histones H2A, H2B, H3 and H4 proteins form a larger octamer which is at the core of a nucleosome.

Question 18

what is a nucleosome?

Answer 18

a structure consisting of the histone octamer and 1.65 wraps of DNA molecule around it.

Question 19

what structure on the nucleosome plays an important role in the transcriptional activity of the DNA?

Answer 19

the ends of the histone molecule which protrude onto the surface of the chromatin/DNA and can be chemically modified.

Question 20

how does chromatin overcome the problem of being too condensed, making the DNA inaccessible?

Answer 20

it makes part of the chromosome accessible by relaxing the compaction level.

Question 21

what are the two main types of chromatin?

Answer 21

> Euchromatin - relaxed, more easily transcribed, genes are most likely located here.
heterochromatin - compact, transcriptionally silent.

Question 22

what are the two main types of chromatin?

Answer 22

> Euchromatin - relaxed, more easily transcribed, genes are most likely located here.
heterochromatin - compact, transcriptionally silent.

Question 23

what is a locus?

Answer 23

> the address on the chromosome where genes are located.

>the information content of a gene is determined by the DNA sequence at a locus.

Question 24

what is a locus?

Answer 24

> the address on the chromosome where genes are located.

>the information content of a gene is determined by the DNA sequence at a locus.

Question 25

what are autosomes?

Answer 25

> the 22 paired chromosomes in the human genome.

> autosomes are of all different size, therefore unequal genetic content.