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1

Polygenic traits

Traits that are influenced/ affected by two or more genes

Mainly influenced by environmental factors such as nutrition and exposure to sunlight

Ex: skin, eye, hair color

2

Mendelian traits

Characteristics that are influenced by ONLY ONE allele/gene

Ex: bloody type, sickle-cell anemia

3

Mendelian vs. polygenic traits

Mendelian influenced by ONE gene

Polygenic influenced by 2 or more genes

4

Principle of Segregation

For any particular trait, the pair
of alleles of each parent
separate and only one allele
passes from each parent on to
an offspring

5

Independent assortment

Genes are passed to offspring independently of each other


The inheritance of one trait does not affect the inheritance of another

6

Phenotype

The observable, physical expression of genotypes

7

Genotype

The genetic makeup of an individual

Refers to an organism’s entire genetic makeup or to the alleles at a particular locus

A, AB , O

8

Gene pool

All the genes shared within a population

9

Antigens

Molecules structures on the surface of red blood cells

• Any molecule that could become a target of the immune system response…

• Substances, such as bacteria, viruses, foreign blood cells, etc. that stimulate the immune
system’s antibody production

10

Allele frequency

In a population, the percentage of all the alleles at a locus accounted for by one specific allele

11

ABO blood group

Consists of 3 alleles

A,B,O

Homo: AA, BB, OO

Hetero: AO, BO

Codominance: AB

12

Macro evolution

Changes produced only after many generations, such as the appearance of new species

13

Micro evolution

Small changes occurring within species, such as changes in allele frequencies

Ex: skin pigment

14

Natural selection

when some individuals of a population are better able
to adapt to their environment and, subsequently, produce more offspring.

• Selective agent: The environment

• Differential productive success between
individuals is the key.

produce more offspring means
greater influence on the gene frequencies of the next generation and are therefore “more fit”

15

Genetic drift

The change in allele frequencies produced by random factors


Occurs more rapidly in small population size

16

Founder effect

A type of genetic drift in which allele frequencies are altered by reproductively isolating a small segment of a population from a
larger population.

Causes the smaller population to
diverge genetically from the parent population

17

Gene flow

Exchange of genes between populations

18

Sickle cell trait

Heterozygous condition in which a person has one Hb^A allele and one Hb^s allele

They have some normal hemoglobin

19

Sickle cell anemia

A severe inherited hemoglobin disorder in which red blood cells collapse when deprived of oxygen

Results from inheriting two copies of a mutant allele

20

Mendel is known for?

He discovered the fundamental principles of how traits are inherited

Did not know about chromosomes