Genetics

Turner's Syndrome

XO

Point Mutations

Change in one base pair of a gene.

Fragile X Syndrome

Abnormally thin section of DNA on X chromosome.

Genomic Imprinting

Gene on one chromosome is silenced while its allele on the homologous chromosome is expressed. This means the same allele has a different affect on the offspring depending on if it arrived in the zygote via sperm or egg.

Nucleotide Excision Repair

If an error is found, a nuclease cuts it out and polymerase and ligase fill in proper pieces.

Single Stranded Binding Proteins

Keep DNA apart during process.

Monosomic

One copy of chromosome missing.

X Inactivation

One of two X chromosomes in a female is randomly inactivated and remains coiled as a Barr body. This occurs when -CH3 groups are added to cytosine. Gene XIST makes this happen.

Guanine 5' Cap

Protects mRNA from hydrolysis.

What direction is DNA read?

3'-5'

What direction is DNA synthesized?

5' to 3'

What direction does tRNA read the mRNA strand?

5'-3'

Test Question 1: Explain how a single base-pair mutant can alter the structure and, in some cases, the function of a protein.

A single base-pair mutant can alter the structure and function of a protein. A mutation is an change in a gene that can lead to a variety of different expressions. There are many types of mutations, such as a point mutation, which only changes one base pair of a gene, and a frameshift mutation, which could shift the anticodons that would code for each codon of the mRNA. If the mutation creates a sequence of amino acids through the process of translation that is different than what the protein was originally meant for, the entire function would change and it could potentially be very harmful or very helpful.

Start Codon

AUG.

Aneuploidy

Abnormal chromosome number.

Poly (A) Tail

Helps with passage out of nucleus and protects mRNA.

Test Question 2: Explain how ligand A and ligand B can cause identical cellular responses in a cell.

Ligand A and ligand B can cause identical cellular responses in a cell because they use the same secondary messenger and activate the same signal transduction pathway.

Erwin Chargaff

Noticed regularity in ratios of bases.

Oswalk Avery

Purified various chemicals from heat-killed pathogenic bacteria to try and transform live non-pathogenic bacteria. Chemical DNA worked.

Base Pair Substitution

Replacement of one nucleotide and complement with another on DNA.

Polyribosomes

Strings of ribosomes that makes many copies of polypeptides quickly.

Maternal Inheritance

The mitochondria passed on by zygote all come from the cytoplasm of the ovum.

Test Question 3: Predict the most likely effect of a two-nucleotide deletion in the middle of the intron located between exons 4 and 5 on the structure of protein A. Justify your prediction.

There is no change because the intron does not contain protein coding information.

Test Question 4: Predict the percent of phenotypic males among the F1 offspring of the cross shown in the Punnett square if the offspring are raised at 22 degrees Celcius.

75%. The Z*Z becomes ZZ at 22 degrees Celcius. Since ZZ's are phenotypic males, so far 2 out of 4 offspring are phenotypic males. Since Z*W individuals still contain there modification after being raised to 22 degrees Celcius, and Z*W's are also phenotypic males, 3/4ths or 75% of the offspring are phenotypic males.

Deletion at #5

Cri du Chat.

Promoter

DNA sequence where transcription begins.

Morgan

Discovered sex linkage using fruit flies. Also discovered that if two genes are located close together on a chromosome, they are likely to be inherited together.

Telomeres

End of DNA that protects against major shortening of DNA by postponing the erosion of genes near the ends of DNA molecules.

Nucleoside Triphosphate

Energy source for DNA replication.

Spontaneous Mutations

Errors during DNA replication, repair, and recombination can lead to base-pair substitutions, insertions, and deletions.

Trisomic

Extra copy of chromosome.

Polyploidy

Extra full sets of chromosomes (occurs in plants).

Nonsense Mutation

If turns to stop codon, it is a nonfunctional protein.

Prader-Willi Syndrome

Inherit abnormal chromosome from dad.

What is located at the 5' end of DNA?

Phosphate group.

The Importance of Introns

Play some regulatory roles in the cell and control gene activity.

Aminoacyl- tRNA Synthetase

tRNA binds the amino acid to itself to be used in translation again.

What is located at the 3' end of DNA?

Hydroxyl group.

Who can a mother pass a sex-linked trait to?

Both daughters and sons.

Alfred Sturtevant

Created genetic mapping and the theory that the father apart genes are on a chromosome, the more chances that crossing over can occur and the higher the recombination frequency will be.

Chromosomal Theory of Inheritance

Genes have specific loci on chromosomes. Chromosomes undergo segregation and independent assortment.

Angelman Sydrome

Inherit abnormal chromosome from mom.

Kleinfelter's Syndrome

XXY.

Who can a father pass a sex-linked trait to?

All daughters but no sons.

Missense Mutation

Altered codon codes for amino acid, but not the correct one.

Frameshift Mutation

Altered reading frame that results from an insertion or deletion.