Unit 4 STEM Test Study Guide

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Heredity

the passing of physical characteristics from parent to offspring

Trait

Each specific characteristic

Examples of traits

stem height, seed color, eye color

genetics

the scientific study of heredity

fertilization

process in which a new organism is formed when egg and sperm cells join

Purebred

the offspring of many generations that have the same traits

What did Mendel Observe?

that only one form of the trait appeared in the F1 generation but in the F2 generation, the lost form of the trait always reappeared in about one fourth of the plants.

Gene (heredity)

the factors that control a trait

Alleles

different forms of a gene

What are an organism's traits controlled by?

the alleles it inherits from its parents. Some are dominant, while other are recessive

Dominant allele

An allele whose trait always shows up in the organism when the allele is present; symbolized by a capital letter

Examples of dominant alleles

brown eyes, tall stem

Recessive allele

An allele that is hidden whenever the dominant allele is present; symbolized by a lowercase version of the dominant allele

Examples of recessive alleles

blue eyes, short stem

Hybrid

An organism that has two different alleles for a trait

What are offspring's traits determined by?

individual separate alleles inherited from each parent

Probability

A number that describes how likely it is that an event will occur

Laws of Probability

predicts what is likely to occur, not what will occur

Punnett Square

a chart that shows all the possible ways alleles can combine in a genetic cross

What is the combination of alleles that parent can pass on to an offspring based on?

probability

Phenotype

An organism's physical appearance, or visible traits.

Genotype

An organism's genetic makeup, or alleles.

Homozygous

An organism that has two identical alleles for a trait

Heterozygous

An organism that has two different alleles for a trait

incomplete dominance

when one allele is only partially dominant

Codominance

when both alleles for a gene are expressed equally

2 forms of DNA

wet and dry form

What does DNA look like?

twisted ladder

What does DNA contain?

the genetic information for cells to make proteins

What does DNA stand for?

deoxyribonucleic acid

Nitrogen Bases

Molecules that contain nitrogen and other elements

4 Nitrogen Bases

Adenine, Thymine, Guanine, Cytosine

A,T,G,C

Gene (genetic code)

A section of a DNA molecule that contains the information to code for one specific protein; made up of a series of bases in a row

Where can DNA be found?

Everywhere in the body except for red blood cells

What does the genetic code specify?

what type of protein will be produced

What forms the genetic code?

the order of nitrogen bases along a gene

DNA replication

the process in which an identical copy of a DNA strand is formed for a new cell

DNA replication steps

1. Two sides of a DNA molecule unwind and separate between the nitrogen bases

2. Nitrogen bases in the nucleus in the nucleus pair up with the bases on each half of the DNA

3. Two identical DNA molecules are formed

How do parents pass traits to their offspring?

through chromosomes

Hypothesis format

If, then, because