Exam One - 1.8 Genetics Overview Flashcards
Genes x Environment = ?
Phenotype
Genome
the DNA found within all of our chromosomes
Genetics
the branch of biology that deals with heredity and variation
Gene
segment of DMA that produces a function product, most often a peptide
Traits
characteristics of an organism (morphological, physiological, and behavioral)
Nucleic Acids
building blocks of nucleotides with made DNA and RNA
Genetic Code
3 base pair sequence of DNA that specifies amino acid
Chromosomes
structures containing DNA, 46 in humans (23 pairs)
Gene expression
transcription -> translation -> traits
Alleles
different forms of the same gene (ex - eye color)
Polymorphisms
small DNA changes in >1% of population, examples include genes for eye, hair, and skin color
SNPs
single nucleotide polymorphisms - responsible for much genetic variation
Genome
the DNA found within all our chromosomes
mutation
change in DNA, whether inherited or spontaneous
Mutagen
cause DNA mutation
Gain of function
mutation adds or increases peptide function
Loss of function
mutation attenuates or stops peptide function, or translation at all
upregulate
gene expression increases
downregulate
gene expression decreases
homozygous
both allels are the same for a given gene loci
heterozygous
the alleles are different for a given gene loci
dominant allele
promotes phenotype when heterozygous
recessive allele
promotes phenotype only if homozygous
Mendelian Genetic square results when crossing two heterozygous parents
RR, Rr, rR, and rr
3:1 ratio
(ex - 3 purple, 1 white flower)
Complete dominance of one allele
heterozygous phenotype same as homozygous dominant phenotype
incomplete dominance of either allele
heterozygous phenotype intermediate between the two homozygous phenotypes (ex. red flower + white flower = pink flower)
codominance
both phenotypes expressed in heterozygotes (ex. blood types)
multiple alleles
in the pop, some genes have more than two alleles
Pleiotropy
one gene affects multiple different phenotypic characters (ex - sickle cell)
Gene mutations have two classifications:
1 - Hereditary
2 - Acquired (somatic)
Hereditary mutations
- inherited
- mutation present in every cell
- “germ line” mutations
If germ line DNA is mutated, the child that grows from the fertilized egg will have the mutation in each of their cells
Acquired (somatic) mutations
- occur only in life
- present only in certain cells
- caused by mutagens (or DNA copy error)
- acquired mutations in somatic cells cannot be passed down to children
Types of DNA mutations
- Base substitutions (silent, missense, nonsense mutations)
- Frameshift (deletions, insertions)
can result in gain or loss of function
What is the most common genetic disease?
cancer
Point Mutation types
substitution
insertion
deletion
Point mutation - substitution
one base is incorrectly added during replication and replaces the pair in the corresponding position on the complementary strand
Point mutation - insertion
one or more extra nucleotides are inserted into replicating DNA, often resulting in frameshift
Point mutation - deletion
one or more nucleotides is “skipped” during replication, often resulting in frameshift
Types of chromosomal mutations
inversion
deletion
duplication
translocation
chrom. mutation - inversion
one regions of a chromosome is flipped and reinserted
chrom. mutation - deletion
a regions of a chromosome is lost, resulting in the absence of all the genes in that area
chrom. mutation - duplication
a region of a chromosome is repeted, resulting in an increase in dosage from the genes in that region
chrom. mutation - translocation
a region from one chromosome is aberrantly attached to another chromosome
Types of Copy number variation
gene amplification
expanding trinucleotide repeat
copy number v. - gene amplification
the number of tandem copies of a locus is increased
copy number v. - expanding trinucleotide repeat
the normal number of repeated nucelotide sequences is expanded
DNA mutation causes
environmental
spontaneous
Environmental mutations from…
radiation (ionizing and non-ionizing)
chemical mutagens
Spontaneous mutations from…
mistakes in DNA repair
What type of mutation causes sickle cell anemia?
- base substitution
- single base = point mutation
- changes GAG to CTG, switching normal glutamic acid for valine
- loss of function mutation
Prevalence of Sickle Cell
- more so in black births 1/365
- hispanic origin 1/16300
thought to be protective against malaria
Symptoms of Sickle Cell
anemia, pain, swelling (hands/feet), frequent infections, delayed growth/puberty, vision abnormality
