Day 11 oct 14th chapter 7 and 8 Mendelian Genetics and Evolution

1. Day 11 October 14th Chapters 7
and 8
Second exam, posted!

2. Chapter 7: Mendelian Inheritance
Family resemblance: how traits are inherited
Lectures by Mark Manteuffel, St. Louis Community College; Clicker Questions by Kristen Curran, University of Wisconsin-Whitewater

3. (note the hand position of each twin)

4. Where do we begin
and our parents end?

6. Selective Breeding: Observing Heredity
Observations are easy – figuring out how is hard!!!

7. Are any human traits
determined by a single gene?
Traits that are determined by the
instructions a person carries at one
gene are called single-gene traits.
9,000 human traits

8. Other traits, such
as height, hair
color, and eye
color, are a bit
trickier.

9. Sexist view of science?

10. True-Breeding

11. 7.4 Segregation: you’ve got two
copies of each gene but put only
one copy in each sperm or egg.

12.  A dominant trait
masks the effect
of a recessive
trait.

15. 7.5 Observing an individual’s
phenotype is not sufficient
for determining its genotype.

17. Phenotypes and Genotypes
 The outward appearance of an individual
is called their phenotype.
 Underlying the phenotype is the
genotype.
• This is an organism’s genetic composition.

18. Surprise???

19. How do we analyze and predict
the outcome of crosses?
 Assign symbols to represent the different variants of a
gene.
 Generally we use an uppercase letter for the
dominant allele and lowercase for the recessive
allele.
 If we don’t know which of the two possible genotypes
the pigmented individual is, we can write A_, where
the “_” is a placeholder for the unknown second
allele, whose identity we aren’t certain of.

22. 7.6 Chance is important in genetics.
Probability has a central role in
genetics for two reasons:
 The first is a consequence of segregation.
 The second reason is that fertilization, too,
is a chance event.

23. Probabilities
 Any gamete produced by an individual
heterozygous for a trait has a 50%
probability of carrying the dominant allele
and a 50% probability of carrying the
recessive allele.

24. Probabilities
 If a male is heterozygous for albinism (Aa)
and a female is homozygous for albinism
(aa), what is the probability that their child
will be homozygous for albinism (aa)?

28. Analyzing Which Individuals Manifest
the Trait and Which Do Not

29. Why do breeders value
“pedigreed” horses and dogs
so much?

30. 7.10 What’s your blood type?
Some genes may have more
than two alleles.
It can be O, A, B, or AB

31. Multiple Allelism
 in which a single gene has more than two
alleles
 each individual still carries only two alleles

32. Inheritance of the ABO Blood Groups
 A, B, and O alleles
 The A and B alleles are both completely
dominant to O.
 The A and B alleles are codominant to each
other.
 Individuals can be one of four different blood
types: A, B, AB, and O.

34. Why are people with type O blood considered “universal
donors”? Why are those with type AB considered
“universal acceptors”?

35. 7.11 Multi-gene Traits
How are continuously varying traits
such as height influenced by genes?
Old wives’ tales suggest a couple of ways for predicting height:
if the baby is a boy, they say to add five inches to the mothers’
height and average that with the father’s height. Or if it is a
girl, subtract five inches from the father’s height and average
that with the mother’s height. Alternatively, the lore says to
just take the child’s height at two years and double it.

36. Polygenic Trait
 A trait that is influenced by many different
genes
Mind-blowingly
complicated!!!

37. Additive Effects
The Tall Gene –
hormones and
bone length
and growth
factors – oh
what happens when the effects of alleles
from multiple genes all contribute to the
ultimate phenotype
my!

38. Why might computer nerds
be more likely to have
autistic children?
•Autism involves 10 or 20 different genes!
•Unusual abilities of perception, analytical
skills, and focus. This idea—called the “geek
theory of autism”

39. 7.12 Pleiotropy: How can one
gene influence multiple traits?

40. What is
the
benefit of
“almost”
having
sickle cell
disease?

41. The SRY Gene
 “Sex-determining Region on the Y-chromosome”
 Causes fetal gonads to develop as testes
shortly after fertilization.
 Following the gonads’ secretion of
testosterone, other developmental changes
also occur.

42. 7.13 Why are more men
than women color-blind?
Sex-linked traits differ in their
patterns of expression in males
and females.

44. If a man is color-blind, did he
inherit this condition from his
mother, his father, or both
parents?

45. men only get
one chance to
inherit the
normal version
of the gene

46. Chapter 8: Evolution and Natural Selection
Darwin’s dangerous idea: evolution by natural selection
Lectures by Mark Manteuffel, St. Louis Community College ; Clicker Questions by Kristen Curran, University of Wisconsin-Whitewater

48. Evolution in Action
8.1 We can see evolution occur
right before us. Therefore,
evolution is a scientific process.

49. Could you breed
fruit flies who could
live longer than 20
hours on average?

50. Populations
are studied

51. When these eggs hatch, do you think
the flies in this new generation will
live longer than 20 hours without
food?

52. Make a prediction: A population of fruit flies was starved until
80% of the flies were dead. The remaining flies were fed and
offspring were produced. What do you expect to see in the next
generation if you repeat the starvation experiment?
1. More flies will be alive after 20 hours.
2. Fewer flies will be alive after 20 hours.
3. Fruit flies fed after 80% of the population is dead
will lay more eggs.
4. No change in the average number of fruit flies
that were alive after 20 hours.

53. Make a prediction: A population of fruit flies was starved until
80% of the flies were dead. The remaining flies were fed and
offspring were produced. What do you expect to see in the next
generation if you repeat the starvation experiment?
1. More flies will be alive after 20 hours.
2. Fewer flies will be alive after 20 hours.
3. Fruit flies fed after 80% of the population is dead
will lay more eggs.
4. No change in the average number of fruit flies
that were alive after 20 hours.

55. After 60 generations the average starvation resistance
of fruit flies was 160 hours! What has happened to
this population of fruit flies?
1. They are genetically identical to the
original population.
2. The are genetically different from the
original population.

56. After 60 generations the average starvation resistance
of fruit flies was 160 hours! What has happened to
this population of fruit flies?
1. They are genetically identical to the
original population.
2. The are genetically different from the
original population.

57. What happened?
 Evolution
• a genetic change in the population
 Natural selection
• the consequence of certain individual organisms in
a population being born with characteristics that
enable them to survive better and reproduce more
than the offspring of other individuals in the
population

58. Does evolution occur?
 The answer is an unambiguous: YES.
We can watch it happen in the lab
whenever we want.
Recall from our discussion of the scientific method
that for an experiment’s results to be valid, they
must be reproducible.

59. Experiments in Evolution
 Dogs?
 Rabbits?

60. In Nature -

61. Why are camels a successful species?

62. Evolution
 How does evolution occur?
 What types of changes can evolution
cause in a population?
 Five primary lines of evidence
 Evolution by natural selection

64. Darwin’s Journey to an Idea
8.2 Before Darwin, most people
believed that all species had been
created separately and were
unchanging.

65. Button started the debate by suggesting the Earth
had to be at least 75,000 years old!

66. Jean-Baptiste Lamarck
 Biologist, early 1800s
 Living species might change over time.
(Was wrong about the mechanism - he thought that change came about
through the use or disuse of features)

67. Charles Lyell
 Geologist
 1830 book Principles of Geology
• Geological forces had shaped the earth and were
continuing to do so.
 Gradual but constant change
This idea that the physical features of the earth were constantly changing would most
closely parallel Darwin’s idea that the living species of the earth, too, were gradually—
but constantly—changing.

68. We know the Earth is constantly
changing
• Fossils of shells have been found high in the
Andes Mountains
• Forest fires wipe out entire species of plants and
animals.
• Rivers flow, and carve out rock, creating two
distinct shores, where different species live.
• Lakes dry up, killing all marine life inside.
• Pollution and Toxic spills kill organisms.
• Volcanoes.
• Humans are changing the earth.

69. In the 1790s, Georges Cuvier began to explore the bottoms
of coal and slate mines and found fossils

70. Why were fossils such a problem for
people at that time?
• This was highly troubling for people at the
time.
http://www.bspcn.com/2009/04/03/11-extinct-animals-that-have-been-photographed-alive/

71. Extinction
• five mass extinctions on earth, and four in the
last 3.5 billion years - many species have
disappeared in a relatively short period of
geological time.
• The "Great Dying" about 250 million years ago,
which is estimated to have killed 90% of species
existing at the time.
• Most extinctions have occurred naturally, without
human intervention: it is estimated that 99.9% of
all species that have ever existed are now extinct.