Genetics E1- Overview

What is the comprehensive analysis of entire genomes, all genes and their interactions?

*uses advanced tech to study complete DNA sequences and genome wide patterns

Genomics

What is the study of individual genes, heredity, and genetic variation that focuses on how traits are inherited & how specific genes function at the molecular level?

Genetics

What is a double helix structure that is organized into functional units called genes?

DNA

What bases are seen in RNA?

Purines: Adenine (A) & Guanine (G)

Pyrimidines: Cytosine (C) & Uracil (U)

What bases are seen in DNA?

Purines: Adenine (A) & Guanine (G)

Pyrimidines: Cytosine (C) & Thymine (T)

How do uracil & thymine differ?

By a single methyl group (CH3)

What structure is responsible for passing genetic information from one generation to the next, composed of tightly packed DNA and associated proteins?

Chromosomes

How many total chromosomes are there?

46

How many chromosome pairs are there?

23 → 22 autosome pairs & 1 sex chromosome pair

What primarily drives sex determination in humans?

SRY gene on Y chromosome→ initiates male gonadal/ testis development

absence of SRY → ovary formation

What encodes proteins for oxidative metabolism and essential RNA molecules (tRNA, rRNA) required for protein synthesis w/in the mitochondrion?

mtDNA

What is the specific physical location of a gene or other DNA sequence on a chromosome?

Locus

What is an allele?

One of two or more variants of a gene that arise by mutation & are found at the same locus on homologous chromosomes

What term describes a genotype or individual having 2 identical alleles for a particular gene (one on each homologous chromosome)?

Homozygous

What term describes a genotype or individual having 2 different alleles for a particular gene (one on each homologous chromosome)?

Heterozygous

What is a gene map?

Diagram showing relative locations of genes & other identifiable DNA sequences on chromosomes

What is the process of determining the specific locations of genes on chromosomes and the relative distances between them?

*also includes methods to ID genetic loci associated w/ particular traits or diseases

Gene mapping

What is genotype?

Genetic makeup of an individual; contains genes that may or may not be expressed

What is phenotype?

Observable expression of genes

Ex: hair & eye color, height, blood type

What is the shorter arm of a chromosome?

p-arm

What is the longer arm of a chromosome?

q-arm

What separates the arms of a chromosome?

Centromere

What is each arm of a chromosome further subdivided into?

Regions, bands (numbered outward from the centromere) & sub-bands

What do the terms p telomere or “ptel” & q telomere or “qtel” refer to?

Ends of the p-arm & q-arm

How is the nomenclature “3p22.1” read?

Chromosome 3, short arm, region 2, band 2, sub-band 1

What is the process where genetic information is transcribed from DNA to mRNA?

Transcription

What is the process of converting the sequence of a mRNA molecule to a sequence of amino acids during protein synthesis?

Translation

During translation, what component of the cell is responsible for reading the sequence of mRNA in groups of 3 bases (codons) to assemble the protein?

Ribosome

What is the triplet of nucleotide bases in the mRNA that codes for a particular amino acid?

Codon

What is a reading frame?

Order of triplet codons, which codes for specific amino acids

What is the reading frame for glutamine (Gin)?

CAA or CAG

What is the reading frame for tyrosine (Tyr)?

UAC

What is the reading frame for isoleucine (Ile)?

AUA

What does the reading frame UAA encode?

Nothing

What is a change in DNA that may aversely affect the host, occurring spontaneously through errors in DNA duplication and repair (MC) or exposure to mutagenic agents?

Mutation

What type of mutation replaces a single nucleotide with another nucleotide?

*MC type of mutation

Substitution

What term refers to replacing pyrimidine for pyrimidine or purine for purine in substitution mutations?

ex: C for T, A for G

Transition

What term refers to replacing pyrimidine for purine or purine for pyrimidine in substitution mutations?

Ex: A for T, C for G

Transversion

What type of substitution mutation occurs when the base pairs get swapped out, but the mutated RNA sequence produces the same amino acid?

Silent mutation

What type of substitution mutation occurs when a nucleotide gets changed and results in a different amino acid in the protein?

Ex: Sickle Cell Anemia

Missense mutation

What type of substitution mutation occurs when a base change causes an early stop codon, resulting in the protein being too short and almost always nonfunctioning?

*worst type of substitution mutation

Nonsense mutation

What type of mutation involves the loss of a section of DNA?

Deletion

What type of mutation involves the addition of one or more nucleotides to a gene?

Insertion

What is the loss or gain of chromosomes?

Aneuploidy

What is the gain of 1 or more complete haploid complements?

Polyploidy

What is the loss/ absence of a single chromosome from a diploid pair?

*results in 2n-1 chromosomes (ex- 45 chromosomes in humans)

Monosomy

What is the gain of 1 chromosome?

Trisomy

What is the failure of chromosomes to separate (disjoin) and move to opposite poles of the division spindle?

Nondisjunction

What condition can result from non-disjunction?

Trisomy 21 (Down Syndrome)

What is the general viability of monosomy?

Typically incompatible with life, resulting in early embryonic loss

Exception: Turner syndrome

What condition results when individuals are missing 1 X chromosome (absence of second sex chromosome)?

Karyotype: 45,X or X0

Turner syndrome

What is the presence of 2 or more cell lines that differ in genetic makeup?

Mosaicism