lecture 2 - variation

Question 1

when we look at trends in variations in populations what is found?

Answer 1

bell shaped curve - many ppl have an average, some are tall and some are small - could be due to environment or genetics

Question 2

what is a genotype?

Answer 2

genetic makeup – kinds of genes that you have

Question 3

what is a phenotype?

Answer 3

expressed traits, things we can measure e.g. height
made up of genotype and environment

Question 4

what is DNA made up of?

Answer 4

2 sugar phosphate backbone (spb)

Question 5

what does DNA do?

Answer 5

Attached to each spb – organise in pairs – bases attract each other, in between is a hydrogen bond, allows the molecule to unzip,
Always pair up in a similar way

Question 6

what are the 4 bases?

Answer 6

guanine and cytosine
adenine and thymine
these can code for 20 diff amino acids used in various proteins

Question 7

what is a gene?

Answer 7

section of the chromosome that codes for a particular protein

Question 8

how do we determine the function and structure of something?

Answer 8

the codes for the bases in the format that amino acids are put together

Question 9

do we all have the same genes?

Answer 9

yes, we just have diff versions of them - diff variants/alleles e.g. green or blue eyes

Question 10

what is transcription?

Answer 10

Start with the DNA molecules – splits down the middle via hydrogen bonds breaking, alongside RNA will form – same as DNA except it has the base uracil – copying process

Question 11

what is translation?

Answer 11

Molecule of RNA – travels out of the nucleus into the cytoplasm, ribosomes form around and reads the code, putting together the amino acids in the way they should and makes the protein

Question 12

what is a stop codon?

Answer 12

tell the ribosome to stop as the protein is complete – can see how many genes there are

Question 13

who discovered the genome?

Answer 13

Crick and Watson
Rosalind Franklin was involved but died before the Nobel Prize was given

Question 14

what is non-coding DNA?

Answer 14

-May be parasitic
-Includes many transposable elements
-Includes many simple sequence repeats
-Some is highly conserved
-Some may serve regulatory functions

Question 15

what is the most common example of a retrovirus?

Answer 15

HIV - injected and can be copied

Question 16

what is a transposable element?

Answer 16

chunks of DNA that are good at getting copied

Question 17

what are simple sequence repeats?

Answer 17

get extra copies added than the original has in cell reproduction

Question 18

when comparing genomes what was an interesting trend found?

Answer 18

the num of genes an organism has doens’t differ that much
- more complex organisms have bigger genomes than more simple

Question 19

can siblings have diff subsets of genes from mum and dad?

Answer 19

yes

Question 20

how are diploid organisms or cells arranged?

Answer 20

in pairs

Question 21

what is mitosis?

Answer 21

cell reproduction - each chromosome splits down the middle so that there are 2 of everything, the bases line up and split again – daughter cells have 46 chromosomes each – 2 cells left which are identical

Question 22

what is meiosis?

Answer 22

one of every kind of chromosome rather than 2
23 chromosomes from dad and 23 from mum – out of these need 1 of each chromosome (1,2,3etc) and only one of each pair gets copied and goes forward into the gametes – this is done at chance so about half come from dad and half from mum

Question 23

what is crossing over?

Answer 23

Chromosomes pair up during the copying process – each decision as to which will be copied will be at random

Question 24

what is a single base substitution? (mutation)

Answer 24

when one base is put in the wrong place

Question 25

what is a simple sequence repeats? (mutation)

Answer 25

get an extra one copied in during mitosis or one fewer than is actually there

Question 26

what is a segmental change? (mutation)

Answer 26

when you get an entire additional chromosome – downsyndrome, extra sex chromosome – XXY, XYY

Question 27

what does it mean if a mutation has no phenotypic effect?

Answer 27

theyre neutral - change in one of the base pairs within a gene but will still code for the same amino acid , redundancy in bio systems – often numerous ways to do stuff in the body so if a mutation is caused it will be taken over by a diff way of doing things

Question 28

what does it mean if a mutation has deleterious effects?

Answer 28

theyre harmful - more ways to get things wrong than make them better – things are so finely tunes, if do it diff most likely will be worse e.g. cystic fibrosis, haemophilia, Huntington's disease

Question 29

How do you find the genetic basis of a phenotypic characteristic?

Answer 29

Collect data from large fams where some individuals have traits or diseases and use them as particular markers on the genomes – to see which are shared with sufferers and non sufferers – can work out what part of the chromosome causes the effect we are seeing More achievable as we have become better at genetics – many genetic markers at the same time – large group of individuals as long as some have the trait and others don’t – can look at the alleles and see which play some roles in it