Biology Topics (So Far..) RECALL ALL

What is a gene?

A segment of DNA that codes for a trait or protein.

What carries hereditary information?

DNA.

What are the 4 nitrogen bases in DNA?

Adenine, Thymine, Cytosine, Guanine.

DNA base-pairing rules?

A-T and C-G.

Uracil (U).

RNA uses what base instead of thymine?

What is an allele?

Different versions of the same gene.

Difference between genotype and phenotype?

Genotype = genetic makeup; Phenotype = physical expression.

What is a dominant allele?

An allele expressed when present.

What is a recessive allele?

Expressed only if both alleles are recessive.

homozygous

Has same alleles (AA or aa).

What is heterozygous?

Different alleles (Aa).

If phenotype is recessive, what must genotype be?

Homozygous recessive.

What does “carrier” usually mean?

Heterozygous.

Heterozygous × heterozygous (Aa × Aa) phenotypic ratio?

3:1.

Heterozygous × heterozygous genotype ratio?

1:2:1.

Heterozygous × homozygous recessive (Aa × aa) phenotype ratio?

1:1.

Homozygous dominant × recessive (AA × aa) phenotype ratio?

All dominant (4:0).

Heterozygous × homozygous dominant (Aa × AA) phenotype ratio?

All dominant.

Heterozygous × homozygous dominant (Aa × AA) genotype ratio?

1:1 (AA:Aa).

What is a test cross?

Heterozygous × homozygous recessive.

Incomplete Dominance & Codominance

What happens in incomplete dominance?

Traits blend.

Red flower × white flower = pink offspring. What inheritance?

Incomplete dominance.

Incomplete dominance phenotype ratio (heterozygous × heterozygous)?

1:2:1.

What is codominance?

Both alleles expressed equally.

Example of codominance?

Blood type AB.

How many traits are tracked in a dihybrid cross?

Two.

Classic heterozygous dihybrid ratio?

9:3:3:1.

What genotype usually appears in dihybrid examples?

RrYy × RrYy.

If question involves 2 traits, which cross is likely used?

Dihybrid.

Universal donor?

O negative.

Universal recipient?

AB positive.

Blood type A genotypes?

IAIA or IAi.

Blood type B genotypes?

IBIB or IBi.

Blood type AB genotype?

IAIB.

Blood type O genotype?

ii.

Which blood type shows codominance?

AB.

No.

Can two blood type O parents have a blood type A child?

AB × O can produce what offspring blood types?

A or B only.

Central dogma?

DNA → RNA → Protein.

mRNA function?

Carries genetic message from DNA.

tRNA function?

Brings amino acids to ribosome.

rRNA function?

Forms ribosomes.

Which RNA carries amino acids?

tRNA.

Which RNA carries genetic instructions?

mRNA.

Which RNA is structural component of ribosome?

rRNA.

Purpose of mitosis?

Growth and repair.

Purpose of meiosis?

Gamete production.

Mitosis produces how many cells?

2 identical cells.

Meiosis produces how many cells?

4 genetically different cells.

Which process halves chromosome number?

Meiosis.

Why are males more likely to show X-linked disorders?

They only have one X chromosome.

Common X-linked disorders?

Color blindness, hemophilia.

Monohybrid phenotype ratio?

3:1.

Monohybrid genotype ratio?

1:2:1.

Test cross ratio?

1:1.

Incomplete dominance ratio?

1:2:1.

Dihybrid ratio?

9:3:3:1.

One trait only = ?

Monohybrid.

Dihybrid

Two traits = ?

Blending trait = ?

Incomplete dominance.

Gene

A segment of DNA that codes for a specific protein

DNA

It has a double helix structure and is made of nucleotides

Adenine, Thymine, Guanine, Cytosine

These are the four nitrogen bases in DNA

Alleles

This refers to the different versions of the same gene

Genotype

This is the genetic makeup and is expressed in letters

Phenotype

This is the physical expression of a gene

Dominant Allele

This allele is expressed as a capital letter

Recessive allele

This allele is expressed as a lowercase letter

Homozygous

This means that there is only one type of allele present

Heterozygous

This means that there are two types of alleles present

Law of Dominance

This law says that one dominant allele masks a recessive allele

Gregor Mendel

The father of genetics

Pea plants

What plants did the father of genetics work with>

Law of segregation

This law of genetics states that allele pairs separate during gamete formation

Law of independent assortment

This law of genetics states that genes for different traits assort independently. Ex. The gene for height is different from the gene for eye color.

9:3:3:1

What is the classic ratio of the dihybrid cross?

1:2:1

What is the genotypic ratio of incomplete dominance?

3:1

What is the phenotypic ratio of a Heterozygous gene x Heterozygous gene?

1:1

What is the phenotypic ratio of a heterozygous x homozygous recessive?

4:0

What is the phenotypic ratio of a Heterozygous x Homozygous dominant?

IAIA or IAi

What are all the possible alleles for blood type A?

IBIB or IBi

What are all the possible alleles for blood type B?

ii

What are the possible alleles for blood type O?

all of them

What are the possible blood types can a Type A mother and Type B father produce?

O-

What is the universal donor?

AB+

What is the universal recipient?

Mutation

A change in the DNA sequence

Adenine, Uracil , Cytosine, Guanine

What are the four bases of RNA?

MRNA

It carries genetic code from the DNA to the ribosome

tRNA

It carries amino acids to ribosome

rRNA

It forms part of ribosomes

DNA → RNA → PROTEINS

What is the flow of genetic information?

Transcription

The process of information moving from the DNA to the RNA

Translation

The process of information moving from the RNA to the protein

Codon

A 3 base sequence is called a?

nucleus

Transcription occurs here

ribosome

translation occurs here

What is ecology?

The study of interactions between organisms and their environment.

What is the difference between habitat and niche?

Habitat is where an organism lives; niche is its role/function in the ecosystem.