Lecture 13

Question 1

Australopithecus

Answer 1

• 2-4 MYA (S. Africa)
• bipedal, not a tree dweller
• several species
• flat skull bases
• stood 4’-5’ tall
• human like teeth
• brain size of a gorilla’s (small)
• hunter-gatherer lifestyle

Question 2

A. afarensis

Answer 2

“Lucy”
-3.6 MYA
Larger brain, more human like skull, less prominent face

Question 3

Homo habilis

Answer 3

2. 3 MYA
   - humanlike cave-dweller
   - cared intensely for young
   - first to use tools extensively (habilis means handy)
   - coexisted with and was followed by homo erectus

Question 4

Homo erectus

Answer 4

1 MYA

• shallow forehead, massive brow ridges, brain about 1/3 the size of modern humans
• angled skull-base, possible speech
• social, cooperative, used fire
• male-female pairs
• found in China, Java, Africa, Europe, and SE Asia
• Pockets may have persisted until about 35,000 years ago

Question 5

When did homo sapiens first appear?

Answer 5

“The wise human” probably fist appeared about 200,000 years ago

Question 6

Homo sapiens idaltu

Answer 6

• lived about 156,000 years ago
• physically similar to modern humans
• probably resembled an Australian aborigine

Question 7

Homo neanderthalensis

Answer 7

• Split from the human lineage about 516,000 years ago
• Lived all over Europe
• Larger brains, prominent brow arches, muscular jaws, distinct spacing of teeth, and large barred-shaped chest

Question 8

when did Neanderthals disappear?

Answer 8

by 28,000 years ago

Question 9

Otzi, the ice man

Answer 9

a peserved man, frozen in ice from about 5,200 years ago, died about 3300 BC

• it was found in the Schnalstal glacial in 1991
• genetically similar to modern soutjer European populations of Sicily and Sardinia

Question 10

Neanderthals revisted

Answer 10

• They had variants of the FOXP2 gene (possible speech)

- Some had mutations in the MC1R gene (had pale skin and red hair)

Question 11

Denisovans

Answer 11

Nuclear sequences suggest Denisovans separated from Homo sapiens and Neanderthal about 1 million years ago.
-Remains found in a cave in Sivera and probably once widespread in east Asia.

Question 12

Mitochondrial DNA (mtDNA)

Answer 12

• used to trace maternal lineage

- lack of DNA repair in mitochondria leads to a faster mutation rate

Question 13

Y chromosome

Answer 13

• sons inherit it form their fathers

- used to trace male lineage

Question 14

Mitochondrial “Eve”

Answer 14

mtDNA sequences of indigenous peoples worldwide were compared to determine the common ancestral mtDNA sequenced

Question 15

Hypothetically, when and where did ancestral woman live? Who also lived around this time?

Answer 15

~170,000-200,000 years ago in Africa.

-This is remarkably close to the date of the homo sapiens idaltu fossils (~156,000)

Question 16

What supports the Out of Africa hypothesis

Answer 16

mtDNA
Y chromosome
autosome sequences

Question 17

Hypothesis 1 of expansion of modern humans from Africa to the rest of the world

Answer 17

1. Out of Africa or replacement hypothesis
   - Within Africa, Homo sapiens evolved from Homo erectus.
   - descendents migrated from Africa about 60,000 years ago to replace hominids living in Europe, Asia and Middle East

Question 18

Hypothesis 2 of expansion of modern humans from Africa to the rest of the world

Answer 18

2. Multiregional hypothesis
   - Homo ererctus migrated out of Africa to Europe, Asia, and Middle East
   - Evolution of homo sapiens occured in multiple locations with interbreeding between populations

Question 19

Distinctive genetic nametag that Native Americans carry

Answer 19

5 mtDNA and two Y chromosome haplogroups

Question 20

what is a mutation and where does it occur

Answer 20

a mutation is a change in a DNA sequence and occurs at the DNA or chromosome level

Question 21

Polymorphism

Answer 21

a genetic change that is present in > 1% of a population

Question 22

The effects of mutations

Answer 22

loss-of-function

gain-of-function

Question 23

“loss-of-function” mutations

Answer 23

recessive

Question 24

“gain-of-function” mutations

Answer 24

dominant

Question 25

germline mutations

Answer 25

- originate in meiosis | - affect all cells of an individual

Question 26

somatic mutations

Answer 26

- originate in mitosis | - affect only cells that descend from changed cell

Question 27

Examples of mutations that cause disease

Answer 27

beta globin gene | collagen genes

Question 28

What agent causes a mutation and how does it occur?

Answer 28

agent = mutagen | -occur spontaneously or by exposure to a chemical or radiation

Question 29

Spontaneous mutation

Answer 29

- de novo or new mutation - not caused by exposure to known mutagen - result from errors in DNA replication - DNA bases have slight chemical instability

Question 30

what alternating forms do spontaneous mutation exist in?

Answer 30

tautomers | -as replication form encounters unstable tautomers, mispairing can occur

Question 31

Does the larger or smaller genes have higher mutation rates?

Answer 31

larger genes | -but each human gene has about 1/100,000 chance of mutatng

Question 32

why do mitochondrian genes mutate at a higher rate than nuclear genes

Answer 32

becaust mtDNA cannot repair their DNA

Question 33

How can estimates of mutation rate be derived?

Answer 33

from observation of new dominant alleles -for autosomal dominant genes, mutation rate - # of new cases.2X where X - # of individuals examined