Bio Genetics, LT1.3/LT1.4

Note:

+21, +13, etc basically means that there is an extra chromosome at that space

If a cell begins meiosis with two pairs of homologous chromosomes, how many chromosomes will be in each cell that is produced at the end of Meiosis I?

2

In mice, the ability to run normally (R) is a dominant trait. Mice with this trait are called running mice. The recessive trait (r) causes mice to run in circles only. Mice with this trait are called waltzing mice. Hair color is also inherited in mice. Black hair (B) is dominant over brown hair (b). Cross two dihybrid running, black mice using a Punnett square on scratch paper. Assuming the alleles assort independently during Meiosis, what phenotype ratio do you expect in the offspring?

9 running, black mice, 3 waltzing, black mice, 3 running, brown mice, 1 waltzing, brown mice

pedigree

A chart or "family tree" that tracks which members of a family have a particular trait

codominance

A condition in which both alleles for a gene are fully expressed. EX both blue and red scales, instead of brown

dihybrid cross

A cross between individuals that have different alleles for the same gene

karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

The START codon is always

AUG

How do meiosis and sexual reproduction increase genetic variation

All of the above

True or Pure breeding

All offspring displayed one form of the characteristic/Allele, Homozygous Alleles

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recessive

An allele that is masked when a dominant allele is present

Heterozygous

An organism that has two different alleles for a trait

Homozygous

An organism that has two identical alleles for a trait

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

An organism's physical appearance, or visible traits.

first-division nondisjunction

At 1st meiotic division, homologous chromosomes move to the same pole at anaphase. Sperm will be Disomic and Nullisomic, and zygotes will be trisomic and monosomic

second-division nondisjunction

At 2nd division meiosis, sister chromatids move to the same pole at anaphase. Gametes are 1 disomic, 1 nullisomic, and 2 Euploid. Zygotes are trisomic, monosomic, and euploid (50%)

How to identify an x-linked dominant trait

Both males and females equally affected all affected males have an affected mother or father All affected females have an affected mother or father Female progeny of trait showing father are usually affected

In sheep, Black coat color (B) is dominant over white (b). A farmer has a black male but doesn't know the genotype. What cross could he perform to figure this out? Show all work using a punnett square on scratch paper. Write a statement on your scratch paper explaining how he would know the genotype of black male depending on the phenotypes of the offspring using an If, then sentence.

C: black male with white female, genotype bbThis

sex chromosomes

Chromosomes that determine the sex of an individual

What occurs during Prophase 1 of Meiosis that leads to vast genetic diversity

Crossing Over

What is DNA methylation?

DNA Methylation is the addition of a methyl group to cytosine in a DNA molecule. Methylated cytosine can then recruit proteins that interfere with the binding of transcription factors.

What are Genetic markers?

DNA sequence variations that can alter the accessibility of RNA Polymerase and can affect regulatory elements such as promoter regions. Created through mutations (environmental factors and genetics)

dominant

Describes a trait that covers over, or dominates, another form of that trait.

alleles

Different forms of a gene

RNA polymerase

Enzyme similar to DNA polymerase that binds to DNA and synthesizes a strand of mRNA from a DNA "template."

Helicase

Enzyme that unzips DNA

Mutations in DNA that are sources of genetic variation can result from

Errors in DNA replication Exposure to UltraViolet (UV) radiation Exposure to mutagenic chemicals, for instance in cigarette smoke

45, X

Female with Turner syndrome

What happens during the Acetylation of histones

Genes are expressed

What happens during the Methylation of histones

Genes are repressed

What are histone modifications

Histone modifications are the modifications of histones which are the proteins which DNA is wrapped around to create chromatin. Acetylation of histones and Methylation of histones lead to different outcomes

What is the random distribution of homologous chromosomes in differing combinations in sex cells called?

Independent assortment

How to identify an autosomal dominant trait

Males and Females have the same chance of inheriting the trait If the trait is displayed in offspring, at least one parent must show the trait If not in either parent, should not be in either child unless there is gene amplification involved Homozygous for dominant condition is typically more severe (prominent) If both parents posses trait but their progeny do not, then both parents must be heterozygous.

How to identify an autosomal recessive trait on a pedigree

Males and Females have the same chance of inheriting the trait You can only express the trait if homozygous If both parents express the trait, their progeny should too If progeny express traits, and the parents don't, both parents are heterozygous Trait can skip generations If one parent expresses trait, their non affected progeny are heterozygous carriers

How to identify an x-linked recessive trait

More common in males than females If mother has trait, then all sons have the trait Son of female carrier as a 50% chance of getting the trait

46, XX

Normal female karyotype

46, XY

Normal male karyotype

F2 generation

Offspring resulting from interbreeding of the hybrid F1 generation.

Mendel performed a cross between a true-breeding pea plant with purple terminal flowers and a true-breeding pea plant with white axial flowers. Purple (P) is dominant over white (p); axial (A) is dominant over terminal (a). What were the two genotypes he was crossing? What were the phenotypes of the offspring?

PPaa x ppAA, Offspring Ph: All purple, axial

P generation

Parental generation, the first two individuals that mate in a genetic cross

47 XX(or XY) +21

Person with Down syndrome

47 XX (or XY) +13

Person with Trisomy 13, aka Patau syndrome

steps in protein synthesis.

RNA polymerase makes a mRNA copy of the desired DNA strand mRNA travels outside of the nucleus to a waiting ribosome The ribosome binds to the mRNA and reads the codons until it finds a START codon An anticodon on tRNA matching the current mRNA codon is brought into the ribosome The tRNA connects the corresponding amino acid to the growing protein The empty tRNA moves out of the ribosome and the mRNA moves to the next codon The ribosome stops reading at the STOP codon The ribosome lets go of the protein, which will occasionally fold to turn into its functional state.

Incomplete dominance

Situation in which one allele is not completely dominant over another allele. EX brown scales (red and green alleles)

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The making of an mRNA based off of a template strand of DNA is known as...

Transcription

What controls when the body expresses certain genes

Transcription Factors, Genetic Markers, Epigenetics (Histone modification/DNA Methylation)

What are transcription factors and what do they do?

Transcription factors are proteins that bind to specific DNA sequences. Activity of these proteins can be controlled by environmental cues. These factors recruit RNA polymerase to the region, and can indirectly control when certain genes are expressed

The process by which an mRNA molecule is 'read' by the ribosomes in order to create protein is known as

Translation

RNA Polymerase performs a proofreading function.

True

The STOP codons are:

UAA, UAG, UGA

Monohybrid cross

a cross involving one trait in which both parents are heterozygous for a trait

Euploid

an individual with the appropriate number of chromosomes for their species (n for gametes) (2n for zygotes)

A cross between two pea plants that produce yellow seeds results in 124 offspring - 93 produce yellow seeds and 31 produce green seeds. Yellow seeds (Y) are dominant over green seeds (y). What are the likely genotypes of the plants that were crossed

both Yy

What is the evolutionary advantage of sexual reproduction over asexual reproduction

d. It allows for a vast amount of variation in individuals, assuring survival of the species in a changing environment

Germline cells that undergo meiosis start as __________ cells and end as ________________ cells (gametes such as sperm or egg).

diploid/haploid

monosomic zygote

has only one copy of a particular chromosome, instead of 2 (2n-1)

trisomic zygote

has three copies of a particular chromosome, instead of 2 (2n+1)

Nullisomic gamete

is an abnormal gamete with 0 homologous chromosomes instead of 1 (n-1)

Disomic gamete

is an abnormal gamete with two homologous chromosomes instead of one (n+1)

47, XXY

male with Klinefelter syndrome

autosomal chromosomes

non-sex chromosomes

gene expression

process by which a gene produces its product and the product carries out its function

Where does Meiosis occur

sex cells

The amount of genetic variation in offspring is greatest in organisms that reproduce

sexually through meiosisThis

When two true-breeding pea plants that show contrasting traits are crossed in a case of Complete Dominance Inheritance, all of the offspring show

the dominant form of the trait

F1 generation

the first generation of offspring obtained from an experimental cross of two organisms

polygenic

trait controlled by two or more genes

multiple allele traits

traits controlled by a single gene with more than two alleles