week 1 genetics and behavior Flashcards
1
Q
what is Darwins 1859 quote regarding natural selection
A
“evolutionary change occurs as heritable traits of successful individuals are spread throughout the population, whereas those traits of less successful individuals are lost”
2
Q
what did blest 1957 show about the impact of background pattern on consumption of worms by birds?
A
backgrounds that contained eyespot patterns were avoided by birds.
moths that had wings that had these patterns were less likely to be eaten and so had more offspring
3
Q
describe what the peppered moths in the evolution of natural selection
A
there are 2 types of moths - white with dark spots, dark with white spots
white color moths help blend into bright environment and hide from birds
so natural selection of white moths
after industrial revolution, Cole produced pollution and soot. overtime, trees covered in soot so dark moths had an advantage now.
so natural selection of dark moths
but less pollution now as less factories, less soot. so now white moths increase in frequency
4
Q
where is most of the increase in brain size due to evolution
A
cerebrum
5
Q
what do cortical convulsions mean?
A
grooves and folds on the brains surface
6
Q
what have increased convulsions in the cerebrum serve to increase?
A
the volume of cerebral cortex
7
Q
what does higher cortical convulsions lead to
A
higher processing power as higher surface area for neural connections
8
Q
what do humans have the highest of in mammals
A
highest brain size to body weight ratio
9
Q
which animal has a higher brain size to body weight ratio compared to humans?
A
the tree shaw
10
Q
what % of the brain makes up our total body weight?
A
2.3%
11
Q
what % of an elephants brain makes up its body weight?
A
0.2%
12
Q
at birth, how much does a brain weigh and how many neurons does it have?
A
350g and has about 100 billion neurons
13
Q
production of new neurons almost ceases except for where?
A
the hippocampus and olfactory bulb
14
Q
how much does the human brain weigh in adult size?
A
1400g
15
Q
which southern ape species played a significant part in human evolution?
A
australopithecus
16
Q
what was the first hominid to leave Africa around 1.7 million years ago?
A
homo erectus
17
Q
where did Homo sapiens evolve from?
A
east Africa
18
Q
what did Mendel notice from studying peas in his garden?
A
you could get 2 types of peas: brown & white
if you cross fertilize the brown and white peas, you only get brown peas so the brown is DOMINANT. only white would appear if both the things controlling color was recessive white.
the colours were controlled by one thing but there were 2 variations of it
19
Q
what’s the name of the things that control our traits?
A
alleles
20
Q
where are alleles located
A
DNA
21
Q
what is DNA a polymer of
A
nucleotides
22
Q
what is each nucleotide of DNA formed from
A
a deoxyribose (pentose sugar), a nitrogen-containing organic base and a phosphate group
23
Q
what are the 4 organic bases of DNA?
A
adenine, guanine, cytosine, thymine
24
Q
briefly describe the structure of DNA
A
A double helix, with 2 polynucleotide chains, held together by hydrogen bonds between specific complementary base pairs
25
who deciphered the DNA code?
Watson and Crick 1962
26
genes direct the synthesis of what?
proteins
27
what is the function of RNA?
transfers genetic information from DNA to ribosomes
28
how is the DNA or RNA nucleotides joined together?
condensation reaction, forming phosphodiester bonds
29
describe the 5 steps of semi-conservative DNA replication
1. DNA helicase breaks the hydrogen bonds between bases which unwinds the double helix
2. now there's 2 strands which both act as templates
3. free floating DNA nucleotides attracted to exposed bases via specific complementary base pairing, hydrogen bonds form between them
4. DNA polymerase joins adjacent nucleotides on new strand by condensation forming phosphodiester bonds which is the sugar phosphate backbone of DNA.
5. replication is Semi-conservative = each new strand formed contains one original/template strand and one new strand ensuring genetic continuity between generation of cells
30
describe what a gene and allele is and where they are located
A gene is a specific sequence of DNA located at a particular position (locus) on a chromosome. Each gene contains instructions for making proteins that determine various traits.
An allele is a variant form of a gene, found at the same locus on homologous chromosomes. Each individual inherits two alleles for each gene—one from each parent. These alleles can be identical (homozygous) or different (heterozygous), influencing the expression of traits.
31
give the overview (2 steps) of protein synthesis
1. transcription
- production of mRNA from DNA
- happens in the nucleus
2. translation
- production of polypeptides from the sequence of codons carried by mRNA
- happens in cytoplasm of ribosomes
32
where is mRNA made and how
nucleus and by transcription
33
what is the role of mRNA
acts as a template for translation in the cytoplasm
sequence of bases on RNA determines sequence of amino acids in polypeptide chain
34
what is the role of tRNA
has an amino acid attached to it and an anticodon that's complementary to an mRNA codon
35
35
what codes for a specific amino acid
codons - 3 adjacent base pairs
36
36
describe the process of protein synthesis
stage 1 transcription:
1. DNA helicase unwinds 2 DNA strands by breaking hydrogen bonds between complementary base pairs. only 1 DNA strand acts as the template
2. free mRNA nucleotides align and pair with complementary base
3. genetic code carried from nucleus to cytoplasm
stage 2 translation:
1. strand of mRNA attaches to ribosome, which moves along the strand translating each codon into the amino acid using tRNA which lengthens the protein
when ribosome reaches end of mRNA strand, a codon instructs it to release the completed protein.
37
some genes might be on the X chromosome, but not on the matching Y chromosome, what does this mean?
males will only have 1 version of these genes
38
describe the process of meiosis to make sperm cells
1. DNA must replicate so there are 2 copies of each chromosome, called sister chromatids joined by a centromere
2. meiosis 1 - the cell divides to create 2 new cells each with 23 duplicated chromosomes
3. meiosis 2 - division again making 4 haploid cells (sperm cells) with just 23 chromosomes
39
describe the process of meiosis to make egg cells
1. DNA must replicate so chromosomes duplicate
2. cell divides to make 2 cells each with 23 duplicated chromosomes, one of these cells die
3. fertilisation
4. fertilized cell divides to create 2 cells. the cell without sperm dies
5. the sperm and the egg combine to form a zygote with 23 pairs of chromosomes
40
what is gender determined by
1 pair of chromosomes , X or Y
41
Which pair of chromosome is the smallest in humans
Y pair in males - it has less than 200 genes whilst most have 1500
42
a gene is 'sex-linked' if its locus is....
on a sex-chromosome
43
why are x-linked traits eg color blindness or haemophilia more common in males
males (XY) only have one X chromosome—so they only get one copy of the gene. Since they don’t have a second X chromosome to provide a dominant allele that could mask the recessive one, they express whatever allele they inherit on their single X.
In contrast, females (XX) have two X chromosomes, so they need two copies of a recessive allele to express the trait (one from each parent).
That’s why X-linked recessive traits (like color blindness or hemophilia) are much more common in males—they only need one copy to show the trait, while females need two.
44
what is Down syndrome caused by?
a chromosomal aberration resulting in an extra 21st chromosome
45
what is single gene metabolic disorder Phenylketonuria (PKU)?
discovered by norweigan dentist called Asbjorn Folling
PKU Is transmitted by a recessive gene mutation on chromosome 12 - mutation
cannot break down phenylalanine, an amino acid common in food. results in blood build up = brain damage
now hospitals screen babies for high levels of this amino acid
reduction of phenylalanine in diet relieves symptoms
46
summarise the Maze bright Maze dull study by Tryon 1934
Tryon ran a normal population of rats in a maze, then separated the really fast ones at learning the maze and the slow ones, allowed these 2 groups to breed separately
then breed the 2 groups offsprings.
by the 8th generation, the 2 groups behavior in the maze was completely different. all of the bright group learnt the maze quickly, and all of the dull ones slowly
suggesting its genetics making them fast or slow
47
what name is given to the type of breeding performed by Tyron?
selective breeding
48
what did Cooper and Zubek find between the maze bright and maze dull rats?
difference between 2 groups was only seen if both groups were in impoverished environment
Their study demonstrated that environmental factors can significantly impact genetic predispositions. They raised selectively bred 'maze-bright' and 'maze-dull' rats in two different environments. In enriched environments (stimulating, with toys and social interaction), both types of rats performed well in maze tests. In impoverished environments (isolated, minimal stimulation), even 'maze-bright' rats performed poorly. This highlighted the crucial role of environmental conditions in shaping cognitive abilities, regardless of genetic predisposition.
49
how are fraternal and identical twins formed and what is the biological name given to them?
fraternal twins - 2 eggs individually fertilized = dizygotic
identical twins - 1 egg split after fertilization = monozygotic
50
what does social dominance theory suggest
social dominance is adaptive because dominant males produces more offspring than non dominant males
51
what behaviors are not advantageous
1. adopting
2. not identifying chick
52
what did Bouchard 1998 find in a study of Minnesota twins
twins reared apart showed identical twins are more similar than fraternal twins on all psychological dimensions
53
what did turkheimer et al 2003 show about heritability of IQ in twins?
heritability of IQ was near 0 in impoverished twins and near 1 (max) in affluent twins
54
epigenetics
heritable changes in gene function, without changes to the base sequence of DNA, but caused by changes in the environment
55
some disorders like haemaphelia are caused by what?
the presence of a single recessive gene on a male X chromosome
56
what did fisher 2003 suggest about adopting
evolutionary pressure to take on imposter offspring overrides costs of mistakenly rejecting your own
57
what did saino et al 2000 suggest about healthy chicks
it is good to have a healthy chick - sometimes you can bring up loads of chicks in a good season, but in a bad one you have to priorities and give food to only healthy chicks
58
what is sentinel behavior eg in meerkats and what did clutton-brock 1999 say about this
Meerkats take turns standing guard while the rest of the group eats or rests (sentinel behavior). The sentinel climbs to a high vantage point and scans the surroundings for potential predators. If a threat is detected, the sentinel emits a warning call, prompting the group to seek cover. This behaviour increases group survival by allowing others to focus on feeding while still being protected. Sentinels typically assume this role voluntarily after they have eaten, ensuring their own safety before taking on the task.
First to spot predators → Increased survival.
Engaged after feeding, reducing self-risk.
benefiting the individual
59
what is direct fitness
traits that increase ability to survive and contribute large numbers to fertile offspring to next generation
sentinel behavior provides an advantage to the individual as it is the first to see the predator so the first to escape
it does not have a disadvantage in terms of stopping it feeding as the individual will only engage in the behavior after it has eaten
60
what is indirect fitness
traits that increase the ability to help kin survive and contribute large numbers of fertile offspring to the next generation
61
describe alarm calling in Beldings ground squirrel found by Sherman 1977
ground squirrels use vocal alarm calls to warn others of nearby predators. Females, who typically remain in their natal colonies, are more likely to give alarm calls because they are surrounded by close relatives, increasing their indirect fitness by helping kin survive. Males, on the other hand, disperse from their birth colony and are less likely to call since they are usually unrelated to the group. The behaviour is an example of kin selection, where the costs of calling (increased predator attention) are outweighed by the genetic benefits of protecting relatives.
62
what rule do you use to work out when there is enough benefit from indirect fitness for altruistic behavior to evolve?
Hamiltons rule - altruistic behavior would evolve if...
R x b - c > 0
R = relatedness to recipient
b = benefit to the gene pool of act
c = cost of act
63
kin selection only works if...
you recognize your kin
64
what did porter et al 1984 find about mothers and photographs
mothers can recognize photographs of their infants within 33h of births, and strangers can match photographs of mothers to their infants, suggesting a physical resemblance among kin
65
what did porter and moore 1981 find about smelly children and siblings
siblings and mothers can identify clothing worn by individual children in a family, and parents can correctly distinguish between orders of shirts worn by identical twins
66
what did gustafsson et al 2013 find about infants cries
both mothers and fathers reliably recognize their infants cries with experience
67
what does altruistic behavior mean
actions that benefit others at a cost to the individual, without providing a clear evolutionary advantage.
traits are typically considered adaptive if they increase an individual's fitness (i.e., reproductive success). However, some altruistic behaviors appear to reduce an individual's direct fitness, making them seem non-adaptive.
68
indirect fitness will only work if...
you recognize kin
69
what is extreme altruism and give an example with bees and naked mole-rats
bringing up sisters instead of daughters
In eusocial insects eg bees, sisters share more genes than offspring, so helping sisters is beneficial. co-operative behavior is driven by haplodiploidity making sibling care more evolutionary advantageous (75% gene similarity)
in eusocial vertebrates eg naked mole rats: live in highly structured colonies with a single breeding female (queen) and non-reproductive workers that maintain the nest and care for the young. Their social system is reinforced by inbreeding and a harsh external environment, which promotes cooperative survival strategies.
70
what does helping at the nest seen in Florida scrub jays show?
siblings from previous generations help their parents raise siblings from subsequent generations which increase chances their sibling will survive, and ensure more genes passed on through survival of their kin
71
describe how DNA is used to make a protein - feedback answer
The Double helix of a strand of DNA within the nucleus of a cell will seperate, exposing the nucleotide bases. A mesenger RNA will form alonside exposed strand matching the appropriate bases, adenine with thyomine/uracil and cytosine with guanine. This process is known as transcription. The mRNA will then leave the nucleus and move into the cytoplasm while the DNA re-combines. In the cytoplasm ribosomes read the code on the mRNA 3 bases at a time. Each triplet represents a single amino acid which attaches to the ribosome. As the ribosome moves down the mRNA a chain of amino acids is formed and once complete becomes a specific protein. This process is known as Translation
72
Haemophilia is more prevalent in males because the _____ is on only the ___
allele for that trait; X chromosome
73
Hamilton (1964) theorised that an altruistic behaviour would evolve if
the benefit to the gene pool x proportion of shared genetic material was more than the cost to potential raising of offspring
74
Evolution of sentinel behaviour in meerkats can be explained in terms of _______ while alarm calling in ground squirrels can be explained in terms of _____ due to the ____ cost of the latter behavior
direct fitness; indirect fitness ; high
75
How did Hamilto suggest we could predict if an altruistic act might become prevelant in the next generation? Provide an example.
Hamilton’s rule altruistic behaviour would evolve if
R x b – c > 0
R = relatedness to recipient,
b=benefit to the gene pool of act,
c=cost of act
Amount of genes common between human mother and daughter is 0.5, amount common between uncle and nephew is .25. Helping to raise 4 nephews would evolve if it meant you were unable to raise one less daughter than you would normally.
(0.25x 4=1) – (0.5x1=0.5) > 0
Therefore the benefit is greater than the cost and the behaviour would mean more of the genes controling this altruistic trait would survive in the next generation
76
Naked Molerats like bees live within a Eusocial Society and also in common with bees have
one breeding female within the colony.
77
Explain how the genetic make up of Bees could help to explain why worker bees help bring up sisters rather than their own offspring.
Female bees are diploid, they have two sets of chromosomes. Males are haploid, they only have 1 set of chromosomes. Two sisters with the same father will receive half of their chromosomes from their mother and so will share 0.5 of their genetic material in common with their mother. From this maternal genetic material they will on average share 0.25 of all of their genes in common with their sister. They will both receive all of their fathers genes and from this paternal genetic material will thus share 0.5 of all of their genes with their sister. In total the sisters will share 0.75 of their genetic material and this is greater than they would share with their daughters. Thus to maximise passing on of genes it would be better to help raise sisters rather than daughters.
