Chapter 5 Science: Test Prep

Lesson 2 Summary

Geneticists use Punnett squares to predict the possible genotypes and phenotypes of offspring In polygenic inheritance, traits are determined by more than one gene and have many possible phenotypes

Science use

The offspring of two animals or plants with different forms of the same trait

Hereditary

The passing of traits from parent to offspring

Replication

The process of copying a DNA molecule to make another DNA molecule

Deoxyribonucleic acid (DNA)

Chromosomes are made of this and it is an organism's genetic material

Sugar phos-phate groups

Form the sides of the DNA ladder

Substitution Mutation

G and C have been replaced by a T and A in the DNA ladder

Common use

Having two types of components that perform the same function, such as a vehicle powered by both a gas engine and an electric motor

A, B, O, AB

Phenotype blood types

Genotype

The two alleles that control the phenotype of a trait are called the trait's

Same, different

The two chromosomes in an offspring cell may have the ____ or ____ alleles

A and T, C and G

These always bond together on a DNA strand

adenine (A), cytosine (C), thymine (T), and guanine (G)

These are the nitrogen bases that bond and form the rungs of the ladder

Mutations

This can be triggered by exposure to X-rays, ultraviolet light, radioactive materials, and some kinds of chemicals

Substitution, Insertion, and Deletion

Three types of mutations

Trait

Two factors—one from each parent—control each

Cross-Pollination, Self-Pollination

Types of pollination

Dominant

Uppercase represents

Polygenic Inheritance

A genetic condition inheritance pattern in which multiple genes determine the phenotype of a trait

Dominant Trait

A genetic factor that blocks another genetic factor

Codominance

An inheritance pattern in which both alleles can be observed in a phenotype

Incomplete Dominance

An inheritance pattern in which offspring's phenotype is a blend of the parents phenotype

Phenotype

An organism's environment can affect its

Recessive

Lowercase represents

Genetics

The study of how traits are passed from parents to offspring

Insertion Mutation

3 base pairs are added to the DNA ladder

Deletion Mutation

3 base pairs have been removed and other have been added in the DNA ladder

Recessive Trait

A genetic factor that is blocked by the presence of a dominant factor

Punnet Square

A model used to predict possible genotypes and phenotypes of offspring

Nucleotide

A molecule made of a nitrogen base, a sugar, and a phosphate group

Mutation

A permanent change in the sequence of DNA, or nucleotides, in a gene or a chromosome

Gene

A section on a chromosome that has genetic information for one trait

Gene

A segment of DNA on a chromosome

Lesson 3 Summary

DNA is a complex molecule that contains the code for an organism's genetic material, An organism's nucleotide sequence can change through the deletion, insertion, or substitution of nitrogen bases

Phenotype

How a trait appears or is expressed

Heterozygous

If the two alleles of a gene are different, the genotype is

DNA

Is shaped like a twisted ladder which is referred to as a double helix

3:1

Mendel also cross-pollinated hybrid plants. He observed that offspring of hybrid crosses always showed traits in a _:_ ratio

Inherited Trait

Mendel concluded that two factors, one from each sperm and one from each egg, control each

Parent

Mendel's "factors" are part of chromosomes which exist as pairs—one chromosome from each

Effects

Of a mutation depend on where in the DNA sequence the mutation happens and the type of mutation

Substitution Mutation

One nitrogen base is replaced by a different nitrogen base

Deletion Mutation

One or more nitrogen base is left out of the DNA sequence

Insertion Mutation

One or more nitrogen bases is added to the DNA

Hybrids

Plants are called _______ if they come from true-breeding parent plants with different forms of the same trait

AA or AO, BB or BO, AB, OO

Possible blood genotypes

RNA

Ribonucleic acid, a type of acid that carries the code for making proteins from the nucleus to the cytoplasm

Genetic Disorders

Some mutations in human DNA cause

Replication

The 46 human chromosomes contain between 20,000 and 25,000 genes that are copied during

Alleles

The different forms of a gene

Gregor Mendel

The father of genetics

True-Breeding

When a _______ ________ plant self-pollinates, it always produces offspring with traits that match the parent

Homozygous

When the two alleles of a gene are the same, the genotype is

Each cell

____ ____ in an offspring organism contains chromosomes from both parents