Unit 7 Review: Inheritance Unit

9th Grade Honors Biology Unit 7

Define heredity:

Characteristics passed from parent to offspring

Define genetics:

Scientific study of heredity

Define trait:

Specific characteristic of an individual

Define hybrid:

Offspring of crosses between parents with different traits

Define genes:

Factors passed from parent to offspring

Define alleles:

Different forms of a gene

Define probability:

Likelihood an event will occur

Define pedigree:

Chart showing the relationships within a family to analyze the pattern of inheritance of a particular trait

What is the purpose of a Punnett square?

Used to predict the outcomes of a genetic cross by drawing a box table diagram

In a cross, what is the P, F1, and F2 generation?

P: Original parents being crossed

F1: Offspring of the P cross

F2: Offspring from F1 cross

What is a genotype? What is a phenotype?

Genotype: Genetic makeup (2 letter code)

Phenotype: Physical traits, seen, description

How do multiple allele traits differ from polygenic traits? Give an example of each in humans

Multiple alleles: A gene with more than 2 alleles EX: blood type

Polygenic traits: (“many genes”) Single trait controlled by 2 or more genes EX: skin color

How do monohybrid and dihybrid crosses differ? When should FOIL be used? FOIL the following parent genotype: TtRr

Monohybrid: Single-gene or 1-factor cross

Dihybrid: 2 different genes or 2 factors in a cross

FOIL is used for crosses that have more than one gene

TtRr = TR, Tr, tR, tr

What occurs in incomplete dominance? What occurs in codominance?

Incomplete: One allele is not completely dominant over another

Codominance: Phenotypes produced by both alleles are clearly expressed (no mixing/blending)

When certain red (RR) and white (WW) flowers are mated, they exhibit pink flowers. What type of complex inheritance pattern is exhibited?

Incomplete dominance

What does segregation mean? What segregates and goes into the gametes?

Segregation refers to the separation of alleles during gamete formation, alleles segregate and go into gametes during meiosis

Principle of Segregation: Each inherited trait has 2 alleles, 1 allele from each parent is passed to their offspring

When are recessive traits seen or expressed in an individual?

When two recessive alleles are present

Why is Gregor Mendel important to our study of genetics?

By experimenting with pea plant breeding, Mendel developed three principles of inheritance that described the transmission of genetic traits

What does the principle of dominance state? What does the principle of independent assortment show?

Principle of dominance: Some alleles are dominant, others are recessive

Principle of independent assortment: Genes for different traits segregate independently of one another during the formation of gametes

What symbol represents a male in a pedigree? A female? How is a marriage line shown? Offspring produced shown? How are generation shown? Where is the oldest child shown?

Male=square, female=circle, marriage=horizontal line, offspring=vertical line, generation shown=each row w/ roman numeral, oldest to youngest=left to right

How do you know if a trait being traced in a pedigree is dominant or recessive?

If the trait appears in every generation and affects both males and females, it is likely dominant. If the trait skips generations and can be "carried" it is likely recessive.

What are the alleles for blood type in humans? Which is/are dominant, recessive, or codominant?

ii is recessive for type O, IA and IB are codominant - when paired together (IA IB) create type AB

What are the Rh factor alleles? Which is dominant? Which is recessive?

Rh+ is dominant and Rh- is recessive

Which blood type is the universal donor? Which is the universal recipient?

Blood type O is the universal donor, AB is the universal recipient

What are autosomes? What are sex chromosomes? Which numbered pairs are each in human karyotypes?

Autosomes are the first 44 chromosomes or pairs 1-22, sex chromosomes determine an individual's sex and are the last 2 chromosomes

Which parent determines the sex of a child? Why?

Male, half of all sperm cells carry an X chromosome, half carry a Y chromosome, egg cells ONLY carry an X chromosome

What are the sex chromosomes of a male?

XY

What are the sex chromosomes of a female?

XX

What are Barr bodies? How do they form? In which sex are they found?

In female cells, most of the genes in one of the X chromosomes is randomly switched off, forming a dense region in the nucleus known as a Barr body. Barr bodies affect females, as they have XX chromosomes, while males only have one X chromosome which doesn’t shut off and remains active.

Why do males show all sex-linked disorders on the X regardless if they are dominant or recessive?

Since males only have one X, any gene carried on the X is expressed regardless if the trait is dominant or recessive

From which parent(s) do males inherit sex linked traits carried on the X chromosome? From which parent(s) do females inherit sex linked traits carried on the X chromosome?

Genes found on the Y are found only in males and are passed on from father to son. Males receive traits carried on the X from their mother, while females can receive them from both parents.

How does an individual “get” Down Syndrome?

An extra chromosome (trisomy) on chromosome #21

What is nondisjunction?

Failure of homologous chromosomes to separate properly during meiosis

How are Turner’s Syndrome and Klinefelter’s Syndrome similar? How are they different?

Turner’s syndrome (45, X) affects women when one X chromosome is missing, Klinefelter’s syndrome (47, XXY) affects males when an extra X chromosome is inherited, both syndromes cause infertility

What is a genetic disorder?

An expressed phenotype due to a change in a DNA sequence that affects gene expression

Which genetic disorders are caused by recessive alleles? Which are caused by dominant alleles?

Recessive: sickle cell disease, PKU, tay sachs disease, cystic fibrosis

Dominant: achondroplasia (dwarfism), huntington’s disease

TRUE or FALSE: The variation of traits depends on genetic factors (genes) and environmental factors

TRUE