Science Genetics

Genetics

Genetics is the study of how traits are passed.

Why pea plants?

1. 2 possibilities for each plant

2. Produce a large # of offspring

3. Reproduce rapidly

4. Control how peas reproduce

Law of Dominance

States that dominant trait always shows if present

Law of Segregation

States that chromosomes must separate during meiosis

Law of Independent Assortment

States that chromosomes are shuffled before meiosis

Phenotype

Describes your physical traits (hair color, height, etc)

Gene

1. Found on the chromosome

2. Is the trait that can be observed (hair color, height, etc.)

Alleles

Two different types of genes

Genotype

1. Is your genetic makeup

2. Is represented as genes

Homozygous

Same alleles (bb or BB)

Heterozygous

Different alleles (Bb)

Punnet Squares

Is a tool use to predict the possible outcomes of across (mating)

Polygenic traits

More then one gene for that trait(range)

1. Intelligence

2. Personality

3. Height

4. Hair color

5. Skin color

Environmental

Plays a role in gene expression

1. Weight

2. Personality

3. Intelligence

4. Height

5. Skin color

Sex determination

In offspring it is determined by the male

Sex linked traits

Are traits found on the X chromosome

Affects one gender more than the other gender (males bc ½ X chromosome)

Examples: Colorblindness, Hemophilia, etc.

Gene linked traits

Are traits found on the same chromosome inherited together

Codominance

Occurs when both alleles are dominant and show in the phenotype

Examples: blood AB (both dominant)

Multiple alleles

3 or more alleles for a gene

Incomplete dominance

Blending of alleles you get a new phenotype. Neither trait is dominant or recessive.

Karyotype

Is a picture of chromosomes during metaphase.

Shows is you have

• An extra chromosome

• A missing chromosome

• A broken chromosome

Non-disjunction

Occurs when chromosomes fail to separate anaphase and metaphase I or II (+/- a chromosome)

Translocation

Is the crossing over of non-homologous chromosomes

Point mutation

Is a change in one nucleotide (base)

Insertion

Add a base

Deletion

To remove a base

Mutation

Is a any change in # of chromosomes or change in bases

Amniocentesis

Uses the babies skin cells to create a karyotype

Hemophilia

Sex linked trait

Blood doesn’t clog

Sickle-cell Anemia

Red blood cells collapse + can’t carry 02

Carrier shows signs

Cystic fibrosis

Lungs fill with mucus

Down syndrome

Extra 21st chromosome

Caused by non-disjunction

Color blindness

Sex-linked recessive

Can’t see certain colors (red/green)