Genetics

Pedigree chart

a diagram that shows the occurrence and appearance (phenotype) of a particular genetic trait as it is passed from one generation to the next in a given family. A pedigree chart shows how a particular trait runs in a family.

Punnet Square

a grid used to show possible gene combinations. Punnett squares show the possible outcomes of offspring from two parents.

when hybrids with blended traits are mated

pure traits show again in some offspring

blending

combination of genes in which a mixture of both dominant and recessive traits shows, ie. hazel / green eyes, skin color, hair color -ex. SB

DNA

what genes are made up of, it contains hereditary information and controls some activity in the cell.

What is a hybrid trait? (Heterozygous)

Having two UNLIKE genes for a single trait (Tt)

What is a pure trait? (Homozygous)

Having two of the same jeans for a single trait (TT or tt)

What is genetics?

The science that studies the laws of Heredity

pure / homozygous

an organism with two like (same) genes for a single trait. (dominant TT or recessive tt)

hybrid / heterozygous

an organism with two unlike genes for a single trait. (Tt); dominant gene always shows itself over a recessive gene

What is blending?

Combination on genes in which a mixture of both traits show

What are some examples of inherited traits?

Eye color hair color skin color and height

What is a dominant trait?

Usually expressed with a capital letter refers to the stronger pair of traits Ie. brown eyes

What is a recessive trait?

Usually expressed with a lowercase letter Refers to the weaker pair of traits Ie. blue eyes

where are chromosomes located

in the nucleus of a cell

dominant trait

refers to the stronger of a pair of traits, expressed with a capital letter, ie. Brown eyes

recessive trait

refers to the weaker of a pair of traits, expressed as a lower case letter, ie. blue eyes

inherited traits

traits that are passed from parent to their offspring, ie. eye color, hair color, skin color

heredity

passing of traits from parents to offspring

Complete the Punnett square to show the possible offspring Black hair (B) is dominant over brown hair (b) Both parents contain the following genes: (Bb)​ (A) What percentage of the offspring might have black hair? (B) What percentage of the offspring might have brown hair? (C) What is the phenotype of offspring? (D) What is the genotype of offspring?

(A) 75% (B) 25% (C)Black hair, brown hair (D) Bb, bb

if both parents are hybrid for a trait

1/4 - pure dominant 1/4 pure recessive 1/2 hybrid dominant

What is DNA?

Control some activity on the cell it's what genes are made up of

Difference between phenotype & genotype

Genotype are the genes for a particular trait and are represented by two letters; Gg, TT, ee. Phenotype is how the trait is expressed or visible; blonde hair, blue eyes,

What are genes?

Part of chromosomes that controls the inherited traits

What is Heredity?

The passing of traits from parent to offspring

genes

a part of the chromosome that controls inherited traits (like beads on a string); control the life processes of your cells

chromosomes are passed from parent to child

asexual - each daughter cell receives it from the single parent sexual reproduction - daughter cell receives it from each parent cell

how are male represented on a pedigree diagram?

boxes / squares

traits

characteristics of an organism, describing your appearance

melanin

chemical substance that gives skin its color, the more of it means the darker the skin; 4 pairs of genes control skin color, none are dominant

other examples of blending

chicken feathers: pure black BB, pure white WW, or grey BW

how are female represented on a pedigree diagram?

circles

gene symbols

every trait has two genes, one from each parent

genetics

study of heredity; the science that studies the laws of heredity

genotype

the actual gene makeup of an organism (TT, ff, etc.)

Gregor Mendel

the first person to study heredity; "father of genetics"; hypothesized that inherited factors produce certain traits

when one parent is pure dominate and the other is pure recessive

the offspring are all hybrid dominant

phenotype

the way a trait is expressed or visible, such as black hair or blue eyes.

chromosomes

thread-like structures that pass along traits and genetic information / control heredity. "threads of life". the structures found in the nucleus of cells that hold the DNA for an organism. Humans have 46, or 23 pairs