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G and C have been replaced by a T and A in the DNA ladder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