Genetics Exam 3

Proteins

Amino acids are the building blocks of what macromolecule?

Primary structure

This type of structure of a protein is only its sequence of amino acids

Secondary structure

This type of protein structure happens when the amino acids cause the primary structure to fold into an alpha helix.

Tertiary structure

This protein structure happens when the secondary structure folds further.

Quaternary structure

This type of protein structure occurs when two or more polypeptide chains associate.

N^n

This is the expression for the number of amino acids that can be coded for. Use N and n

Number of nucleotides available

In the expression N^n, what does N represent?

Number of nucleotides in the codon

In the expression N^n, what does n represent?

Nearly universal, redundant

What are the two properties of the genetic code?

Wobble base pair

This is a pairing between two nucleotides in RNA molecules that does not follow the Watson-Crick base pair rules. This allows for fewer tRNAs than codons.

Uracil

In a wobble base-pairing, the pairing at the third codon position is relaxed. Because of this, the base G can pair with both C and what other nucleotide?

Reading frame

This refers to one of three possible ways of reading a nucleotide sequence.

Aminoacyl-tRNA synthetase

This enzyme “charges” the tRNA with amino acids and are specific for each amino acid.

Bacterial initiation

At the end of this process, the ribosome is assembled on the mRNA, and the first tRNA is attached to the initiation codon.

Poly-A-tail

In eukaryotes, this is necessary for initiation of translation

Elongation

This is a process in translation when amino acids join to create a polypeptide based on the codons of the mRNA.

Peptidyl site

This site, also called the P site, binds to the tRNA holding the growing polypeptide chain of amino acids during translation.

Acceptor site

This site (A site) binds to the aminoacyl tRNA, which holds the new amino acid to be added to the polypeptide chain.

Exit site

This site (E site) is the final step in elongation. The tRNA is let go by the ribosome at this site.

Release Factor

When the ribosome translates to a stop codon, this pairs up with the A site in order to release the polypeptide from the tRNA in the P site.

Mutations

These are changes in the DNA. These changes can be beneficial, neutral, or detrimental.

Somatic mutation

This type of mutation occurs in non reproductive cells, and therefore will not be passed on to offspring. Instead, they are passed on to new cells through mitosis, which creates a clone of cells that have the mutant gene.

Germ-line mutations

These mutations occur in cells that give rise to gametes, and therefore will be passed on to offspring. These mutations are passed onto approximately half the members of the next generation, who will carry the mutation in all their cells.

Transition

This is a type of base substitution where a purine base transitions into another purine base (A->G or G->A)

Transversion

This is a type of base substitution where a purine mutates into a pyrimidine or a pyrimidine mutates into a purine.

Indels

Word that means “insertion-deletion,” these mutations can result in a frameshift.

Missense mutation

This type of mutation results in an amino acid change. The new codon encodes a different amino acid, which results in an amino acid sequence.

Nonsense mutation

This type of mutation codes for a STOP codon. This results in a premature termination of translation.

Silent mutation

This type of mutation encodes for the same amino acid, thus there is no change in amino acid sequence

Neutral

This is a consequence of a mutation that doesn’t significantly change the protein function. Amino acids often are chemically similar in this outcome.

Loss-of-Function

This is a consequence of a mutation that involves complete or partial loss of normal protein function. It is often recessive.

Gain-of-function

This is a consequence of a mutation that involves the protein gaining a new function. This is often dominant

Conditional

This is a consequence of a mutation that involves the protein only being expressed under certain conditions. An example of this is Himalayan rabbits.

Suppressor mutation

This mutation is one that hides the effect of another mutation at a different site from the original mutation.

Forward mutation

This type of mutation changes the wild type into a mutant phenotype.

Reverse mutation

This type of mutation restores the wild-type gene and its phenotype

Intergenic suppressors

These suppressor mutations occur in a different gene than the original

Intergenic suppressors

These suppressor mutations occur in a different gene than the original

Spontaneous mutation

These mutations occur due to wobble pairing and result in an incorporation error. The final result is a replication error (if the incorporation error isn’t repaired before the next round of replication).

Tautaumerization

This process describes the change in position of a protein. It can be caused by changes in pH and can be catalyzed.

Depurination

In this process, the apurinic site cannot provide a template for a complementary base on the newly synthesized DNA strand. A nucleotide with an incorrect base is incorporated into the newly synthesized strand. The base will then be used as a template, leading to a permanent mutation. A nucleotide is then incorporated into the newly synthesized strand opposite the apurinic site.

Mutagens-intercalating agents

These agents wedge themselves between bases and distort the three-dimensional structure of DNA. Due to this, indels can form during replication. It also causes frameshift mutations.

Polyploid

A cell that contains more than two homologous sets of chromosomes

Allopolyploid

A cell that contains multiple sets of chromosomes from different species

Autopolyploid

A cell that contains multiple sets of chromosomes from the same species

Metacentric

A word to describe a chromosome that has two arms about the same length. The centromere is in the middle of the chromosome.

Submetacentric

A term to describe a chromosome that has one arm longer than the other.

Acrocentric

A term to describe a chromosome with the centromere near one end. This results in one long arm and one “knob.”

Telocentric

A term to describe a chromosome with the centromere at or very near the end of the long arm of the chromosome. This type of chromosome is not present in the human genome.

Chromosome mutations

Rearrangements, aneuploidy, and polyploidy are all categories of what?

Duplication

In a chromosome ________, a segment of the chromosome is duplicated

Deletion

In a chromosome _______, a segment of the chromosome is deleted. This results in the loss of genetic information.

Inversion

In a chromosome _________, a segment of the chromosome is turned 180 degrees. This type of rearrangement depends on the location of the chromosome.

Translocation

In a chromosome _______, a segment of the chromosome moves from one chromosome to a non homologous chromosome or to another place on the same chromosome

Haploinsufficient

When a single normal copy of a gene is not sufficient to produce a wild-type phenotype

Pseudodominance

Expression of a normally recessive allele due to a deletion on the homologous chromosome

Pericentric

This type of inversion involves the centromere. In heterozygotes, this inversion will form an inversion loop and crossing over in the loop forms non-viable gametes. However, this type of inversion also forms recombinant products with duplications and deletions.

Paracentric

This type of inversion does not involve the centromere. In heterozygotes, this type of inversion forms an inversion loop, and crossing over in the loop results in non-viable gametes.

Robertsonian translation

This is a type of translocation that results in a reduced number of chromosomes, as the very small chromosome is usually lost at metaphase.

Alternate

This is one way for a chromosomal structure to segregate at meiosis I. In this way, the N1 and N2 chromosomes will go to one cell, while the T1 and T2 cells go to another cell. This type of segregation will result in viable gametes.

Adjacent-1

This is one way for a chromosomal structure to segregate at metaphase I. In this way, the homologous centromeres will separate. The N2 and T2 chromosomes will migrate to one cell, and the N2 and T1 chromosomes will migrate to another cell. This way of separation results in no viable gametes

Adjacent-2

This is one way for chromosomal structures to segregate at metaphase I. This way in particular is very rare because homologous chromosomes separate together. N1 and T1 will migrate to one cell while N2 and T2 migrate to another cell.

Meiosis 1

This type of nondisjunction will result is no normal zygotes. It will result in trisomic and monosomic zygotes instead

Meiosis 2

This type of nondisjunction will result in 50% normal zygotes, 25% trisomic, and 25% monosomic

Mitosis

This type of nondisjunction will result in trisomic and monosomic cell lines

Aneuploidies

Most human __________ are incompatible with life

Down Syndrome

This syndrome is caused by a trisomy on chromosome 21. It has a wide range of phenotypes. It has maternal age effects and smaller paternal age effects

Trisomy

This is a term that refers to someone having three copies of a chromosome instead of two

Monosomy

This is a term that refers to someone having one copy of a chromosome instead of two

50

Chromosome abnormalities account for nearly ____ % of all spontaneous abortions