genes and environment 1 and 2

Question 1

what is an autosome

Answer 1

chromosomes 1 through to 22

Question 2

what is an allosome

Answer 2

sex chromosome

Question 3

how many pairs of chromosomes do humans have

Answer 3

23

Question 4

what are the chromosomes for females

Answer 4

XX

Question 5

what are the chromosomes for males

Answer 5

XY

Question 6

what are genes

Answer 6

lengths of DNA on the chromosome at the same loci as the homologous pair that codes for proteins

Question 7

what is the estimated number of genes

Answer 7

20,000-25,000

Question 8

what is the estimated number of base pairs

Answer 8

3 billion

Question 9

what are the nucleotide bases

Answer 9

adenine-thymine
cytosine-guanine

Question 10

what is 3 sets of base pairs called

Answer 10

codon which corresponds to an amino acid

Question 11

what percentage of genome codes for proteins

Answer 11

1%, the rest is either junk or regulatory

Question 12

how do amino acids form proteins

Answer 12

combine to form peptides which fold into proteins

Question 13

what are the parts of protein synthesis

Answer 13

transcription and translation

Question 14

what happens in transcription

Answer 14

dna unravelled revealing certain genes
mrna forms mirror copy

Question 15

what happens in translation

Answer 15

mrna leaves nucleus to ribosome
translation in ribosome binds codon to amino acid and forms a peptide

Question 16

what is an allele

Answer 16

same strip of dna with a subtle difference causing slight variation

Question 17

how does sickle cell anemia occur

Answer 17

change of one base pair
example of single nucleotide polymorphism SNP

Question 18

what are SNPs associated with

Answer 18

e.g
-ADHD
-lactose intolerance
-eye colour

Question 19

what is deletion

Answer 19

part of dna missing

Question 20

what is inversion

Answer 20

segment of chromosome removed and reinserted opposite to original orientation

Question 21

duplications

Answer 21

segment copied to homologous pair

Question 22

reciprocal translocation

Answer 22

segments of non homologous chromosomes swap locations

Question 23

what problems can occur when there are mutations with dna

Answer 23

down syndrome- translocation/duplication
turners’- partial deletion
cat eye- duplication
haemophilia- inversion/insertion

Question 24

jacobsen syndrome

Answer 24

-loss from chromosome II
-genes here are critical for development
-symptoms: heart defects, intellectual disability, wide set eyes etc

Question 25

Kleinfelter’s

Answer 25

-extra X chromosome in males
-symptoms: tall, small testicles, lack of facial/pubic hair, breast tissue develops, impaired cog. function, lack of muscle growth

Question 26

what are the two types of genes

Answer 26

dominant or recessive

Question 27

homozygous

Answer 27

two dominant/recessive genes, alleles are the same

Question 28

heterozygote

Answer 28

one dominant and one recessive gene, alleles are different

Question 29

hemizygous

Answer 29

only one allele

Question 30

what are polygenic traits

Answer 30

traits that require multiple genes

Question 31

examples of polygenic traits

Answer 31

eye colour (16+ genes)
height (400 genes)
brain function (6-7000 genes)

Question 32

what are genetic disorders

Answer 32

-disorders have little environmental input
e.g single gene disorders like huntingtons
e.g chromosomal disorders like down syndrome

Question 33

what is genetic vulnerability

Answer 33

-involves many genes and environmental influences
e.g schizophrenia and depression

Question 34

what are SNPs

Answer 34

single nucleotide polymorphisms

Question 35

what SNP is associated with Sz in humans

Answer 35

DISC1

-if DISC1 switched off in mice during last week of fetal development they show symptoms of sz

Question 36

what is the diathesis stress model

Answer 36

links underlying genetic vulnerability e.g nerves fire too fast after consumption of drugs or exposure to stress and environmental stressors

Question 37

environmental influence on expression

Answer 37

some traits develop rigidly
-hand, eye, fixed action patterns FAP, imprinting

some traits are highly flexible
-intelligence in children, religion, height, body fat %

Question 38

what is the epigenetic landscape

Answer 38

metaphor by Waddington 1939
-image represents how some traits take a huge environmental influence to change the course of expression whilst other traits in smaller ridges can easily be changed

Question 39

what are the types of studies into genes

Answer 39

-family studies
-adoption studies
-MZ and DZ twin studies

Question 40

what is behavioural genetics

Answer 40

-research to determine what component of a characteristic is due to genes and shared environment AND what is the other factor
-e.g if there is 80% concordance for MZ twins (genes and shared environment) what causes the remaining 20% to not have concordance (non shared environment)
-this can be repeated on DZ twins, say the concordance is 65% and we know from MZ twins that 20% is due to shared environment then the remaining 15% is genetic differences
-known as the ACE model: Additive genetics, common environment, unique environment

Question 41

what are protective factors

Answer 41

-factors that prevent development of a disorder despite genetic vulnerability and stressors
-e.g personality, coping methods, social support, medication

Question 42

what are examples of external influences

Answer 42

-viruses and other pathogens
-smog
-climate change etc
-epigenetics

Question 43

how do epigenetics impact future generations

Answer 43

a women who smokes whilst pregnant changes 3 generations at once, herself, her daughter and her daughter’s offspring

Question 44

what is DNA methylation

Answer 44

marker scientists use to turn certain instructions on or off