biology: introduction to genetics

Question 1

WHAT IS GENETICS?

Answer 1

Understanding how characteristics are transmitted from parents to offspring
Began with Gregor Mendel
-1800s monk
- Researched pea plant heredity using observations and statistics
– Discoveries made apply to all organisms

Question 2

what is heredity?

Answer 2

Passing of traits from parents to offspring

Question 3

what did mendel do?

Answer 3

Studied seven traits of peas

Question 4

trait

Answer 4

genetically determined variant of characteristic

Question 5

how did mendel study his plants?

Answer 5

pollination experiments

Question 6

pollination

Answer 6

Pollen from anther () transferred to ovary ()

Question 7

self-pollination

Answer 7

Pollen and ovary from same plant

Question 8

cross-fertilization

Answer 8

Pollen and ovary from different plants

Question 9

true-breeding plants

Answer 9

All self-fertilized offspring have same trait as parent

Question 10

what were Mendel’s conclusions?

Answer 10

1. Pair of alleles controls each trait
2. Law of Segregation
3. Law of Independent Assortment

Question 11

allele

Answer 11

different forms of a gene

Question 12

gene

Answer 12

segment on DNA on chromosome that controls trait

Question 13

dominant allele

Answer 13

hides the recessive trait

Question 14

recessive allele

Answer 14

no observable effect on organism if dominant allele is present

Question 15

law of segregation

Answer 15

Paired alleles segregate during meiosis

• Gametes receive one allele from each pair

Question 16

law of independent assortment

Answer 16

• Alleles sort independently during meiosis

* Genes for one trait do not influence inheritance of genes for another trait

Question 17

Molecular genetics

Answer 17

Study of structure/function of genes & chromosomes

Question 18

are all of mendels discoveries still true?

Answer 18

supported by current molecular genetics
each gamete has 1 allele for a gene
each somatic cell has 2 alleles for each gene

Question 19

dominant allele

Answer 19

capitol letters

Question 20

recessive alleles

Answer 20

lower case letters

Question 21

phenotype

Answer 21

Organism’s traits that are expressed

Question 22

genotype

Answer 22

Organisms genetic makeup; consists of alleles

Question 23

homozygous

Answer 23

When both alleles are alike
Ex. PP = homozygous dominant (purple flowers)
pp = homozygous recessive (white flowers)

Question 24

heterozygous

Answer 24

When both alleles are different
Ex. Pp = heterozygous
Since purple (P) is dominant, plant is purple

Question 25

can predictions be made about genetics of offspring?

Answer 25

yes using probability

Question 26

probability

Answer 26

Likelihood that a specific event will occur

Question 27

punnet square

Answer 27

Diagram used to predict genetics of offspring

Question 28

Monohybrid cross

Answer 28

only one trait is tracked

Question 29

testcross

Answer 29

Individual of unknown genotype is crossed with homozygous recessive • Based on probability, can determine unknown genotype Ex. Purple (P?) crossed with white (pp) If no white offspring, what is genotype? probably PP If white offspring, must be Pp

Question 30

dihybrid cross

Answer 30

Two traits are tracked instead of one.

Question 31

what are non-mendelian genetics?

Answer 31

genetics that do not follow mendel's laws 1. incomplete dominance 2. multiple alleles 3. codominace 4. polygenic traits 5. sex-linked inheritence

Question 32

incomplete dominance

Answer 32

``` Heterozygote phenotype is combination of parental phenotypes red snapdragon (CRCR) x white snapdragon (CWCW)
100% offspring are pink(CRCW) ```

Question 33

multiple alleles

Answer 33

A gene with two or more alleles | Ex. Blood type A, B, AB, or O

Question 34

codominance

Answer 34

Both inherited alleles are completely expressed | Ex. Roan coat in cattle

Question 35

polygenic traits

Answer 35

Traits produced by many genes | Ex. Skin color

Question 36

sex-linked inheritence

Answer 36

based on sex chromosomes

Question 37

sex chromosomes

Answer 37

Responsible for determining sex | XX – females; XY - males

Question 38

Y-linked genes

Answer 38

On the Y chromosome Very few genes Mainly code for testes and sperm development; testosterone

Question 39

X-linked genes

Answer 39

On the X chromosome Males- Since only one X, get whatever is on X chromosome Females- Since two Xs, dominant and recessive come into play

Question 40

carrier

Answer 40

Heterozygous for recessive disorder | • Show no symptoms, but may pass recessive allele to offspring

Question 41

is it a problem to have 2 Xs in females?

Answer 41

no; in fetus cells randomly switch off one chromosome or the other

Question 42

are some genes inherited together? why?

Answer 42

yes! Linked genes Genes that tend to be inherited together because they are located close together on the same chromosome

Question 43

how do you tell how far apart genes are on chromosome?

Answer 43

Genes far apart on a chromosome are more likely to crossover. Use crossover frequency to create a genetic map.

Question 44

what else impacts phenotype?

Answer 44

1. Environmental conditions like pH 2. Sunlight 3. Temperature 4. Diet