Genetic Inheritance

Question 1

Genotype

Answer 1

• Refers to the genes of an individual

- Decides which of a parents two alleles will be inherited by the child

Question 2

Genes

Answer 2

• Units of heredity
• Carried in DNA
• Code for protien sythesis

Question 3

Locus

Answer 3

The position of a gene or mutation on a chromosome

Question 4

Allele

Answer 4

An allele is one of two or more versions of a gene. They can be recessive or dominant

Question 5

Recessive Alleles

Answer 5

Hidden by dominant allele. Two recessive alleles are needed for the appearance of their resulting trait.

Question 6

Dominant Alleles

Answer 6

Only one dominant allele needs to be dominant for the appearance of their trait

Question 7

Why don´t dominant traits always prevail in a population (or why might a recessive trait prevail)?

Answer 7

The alleles on genes may be dominant, but the gene itself might be rarely expressed.

Question 8

How are dominant alleles expressed?

Answer 8

With a capitol letter

Question 9

How are recessive alleles expressed?

Answer 9

With a lower case letter

Question 10

Why might a trait is seen in neither of the parents pop up in a child?

Answer 10

Since humans receive two alleles, (one from each parent) recessive alleles could be present, but not shown as visible traits. If two parents who are heterozygous (Aa [using ´a´ as an example) for a trait have a child, and the allele passed down by each parent is recessive, then the child would homozygous recessive, and therefore show the trait.

Question 11

Phenotype

Answer 11

The physical appearance of a trait is determined by proteins (gene products). Determined by genotype, because the genotype refers to the genes, and alleles are the specific forms of genes, and whether an allele is recessive or dominant determines a physical trait (aka phenotype)

Question 12

One trait cross

Answer 12

• Examines the patterns of inheritance of only a single set of alleles for a single characteristic
• Often referred to as monohybrid cross

Question 13

Two trait cross

Answer 13

• Two trait cross explores the patterns of inheritance of alleles for two different characteristics.
• Also referred to as dihybrid
• (We usually have thousands of trait crosses, but it is too hard to represent that)

Question 14

Gamete

Answer 14

• Have 23 chromosomes (haploid)
• Diversity is achieved through crossing over
• Gametes combind to form a zygote

Question 15

Autosomes

Answer 15

• Chromosomes 1-22

-

Question 16

Autosomal Dominance

Answer 16

• The gene for the trait is carried on the autosome, and one only has to have one allele to express the trait

Question 17

Autosomal Reccessive

Answer 17

• You need two copies of the recessive gene to express the trait

Question 18

X linked patterns of inheritance

Answer 18

• genes that are carried on the x chromosome
• x linked dominant means you only mean one gene to inherit the trait
• x linked recessive means you need two genes to inherit the trait

Question 19

Y linked patterns of inheritance

Answer 19

• genes that are carried on the y chromosome

Question 20

Pedigrees

Answer 20

• Used to determine patterns of inheritance
• Chart of family history used to predict the likelihood of having a particular gene
• Circles= female
• Squares= male
• Colored shapes= affected induvidual

Question 21

What phenotype ratio is always observed in a heterozygous x heterozygous dihybrid cross?

Answer 21

9:3:3:1

Question 22

Autosomes

Answer 22

Chromosomes 1-22

Question 23

Sex Chromosomes

Answer 23

• Chromosomes that determine one´s gender
  Males chromosomes´ XY
  Females’ chromosomes´ are XX

Question 24

Gametes that determine gender

Answer 24

Males: Spermatids (sperm)
Females: Oogocytes (eggs)

Question 25

X linked genes

Answer 25

Alleles on an X chromosome

Question 26

Y linked

Answer 26

Alleles on the Y chromosome

Question 27

X linked disorders

Answer 27

• Disorders found on the X chromosome
• Only males can have Y- linked disorders.
• X linked disorders are more common in men because the men only have to have to get one chromosome (the x) to get the disorder while females have to get 2
• Females can have an X linked disorder

Question 28

Polygenic Traits

Answer 28

• Controlled by more than one set of alleles

Question 29

Polygenetic Inheritance

Answer 29

• A trait that is inherited, that requires the inheritance of several genes

Question 30

Multifactorial Traits

Answer 30

Traits that are subject to multi factors (ex environmental influences)

Question 31

Pleiotropy

Answer 31

Occurs when a single mutant gene affects two or more distance and seemingly unrelated traits

Question 32

Incomplete Dominance

Answer 32

Occurs when the heterozygote is intermediate between the two homozygotes

Question 33

Codominance

Answer 33

Occurs when alleles are equally expressed in a heterzygote

Question 34

Multiple Alleles

Answer 34

The gene exists in several allelic forms