BSC Genetics Flashcards
define gene
unit of heredity and are instructions that make up body’s blueprint
- code proteins that determine characteristics
- 35K genes
- come in pairs made of DNA
define mutation
genetic disorders caused by 1+ changes, preventing the gene from functioning properly
- allelic variants that are associate w/ disease
define locus
physical location of a gene
define allele. how many copies do humans have
different versions of genes such as eye color brown vs blue
- 2 copies of all autosomal genes
what is the DNA molecule composed of
5C sugar (deoxyribose)
phosphate molecule
nitrogen base (A,C,G,T)
what is the central dogma
replication, transcription, and translation
DNA to mRNA through transcription, and mRNA to protein through translation
define codon
building block of proteins, code for AAs
- start codon is AUG stop codon UAA, UAG, UGA
what is the anti-codon
complementary RNA code that tRNA has
describe each section of 7q21.13 locus
chromosome 7
q arm
21 band
13 subband
what is a polymorphism
allelic variant not associated w/ disease
what are the 2 types of mutations and what are examples of each
gene (point, frameshift, and in-frame)
chromosome (deletion, insertion, inversion, duplication and translocation)
define point mutation and describe
alteration in a single base pair
- missense, single base pair changes AA for a codon. abnormal/ unstable protein structure
- nonsense, premature stop codon/ abnormal/ unstable protein structure
define frameshift and in-frame mutation and describe
frameshift- number deleted/ inserted is not a multiple of 3, abnormal protein or no protein
in-frame: number of deleted/ inserted is a multiple of three/ may still function even tho different
define phenotype
measurable trait such as eye color or height
define genotype
genetic makeup of an organism at a single locus
define proband
person who brought attention to medical prof. about disease, may not be where disease actually began
define Mendelian disorders
inheritance patterns for single gene disorders classified based on whether they are autosomal, X-linked, and whether they have a dominant or recessive pattern of inheritance
describe autosomal dominant inheritance
one copy of a disease allele is necessary
- all indiv’s have at least one parent who carries diseased allele, vertical transmission
- ex: huntington disease
describe huntington disease
defective gene on chromosome 4, frameshift mutation, includes chorea (jerky random movements, decline in thinking, mood changes)
describe autosomal recessive inheritance
2 copies of a disease allele required
- parents are usually not affected but gene carriers
w/ 2 parent carriers
- 1/4 offspring will inherit 2 copies
- 1/2 offspring will be a carrier
- 1/2 offspring will have no copies of disease
what are examples of autosomal recessive inheritance
sickle cell disease (anemia) and cystic fibrosis
- observed more frequently in consanguineous relationships
describe sickle cell disease
- point mutation in B globin gene, changing from AA6, glu -> val
- resultant hemoglobin is called hemoglobin S (HbS)
- have reduced oxygenation and are more adherent to vascular endothelium
describe x- linked dominant inheritance and an example
only one copy of a disease allele on x chromosome is needed
- males affected more severely
- female affected: preg. has 50% chance to inherit diseased allele
- male affected: all daughters affected but not sons
- fragile x syndrom
describe fragile x syndrome
decreased/ absent levels of fragile x mental retardation protein (FMRP)
- insertion of extra base pairs (like Huntingtons)
- big balls, ears, forehead and chin w/ long and narrow face
describe x- linked recessive inheritance and an example
two copies of a diseased allele on x chromosome
- any male w/ 1 copy is affected
- female carrier: 50% sons/daughters inherit disease
- male carriers transmit disease to all daughters and none to sons
example: hemophilia A
describe hemophilia A
factor BIII deficiency b/c mutations point and frameshift occur in this gene at Xq28
- get blood clotting factors infused
what is complex inheritance
interactions of variations in multiple genes and environmental factors
- include heart disease, diabetes, and asthma
what are the 5 chromosome mutations
1) duplication
2) inversion
3) deletion
4) insertion
5) translocation
which gene has an impact on periodontal disease? what tests can we run to assess caries/ periodontal disease
- no gene has been identified that has as large of an impact on periodontal disease as environmental influences like smoking and diabetes mellitus
- clinical measurements remain the best approach of assessment
which genes are believed to impact caries
ameloblastin, aquaporin 5, enamelin, mucin 5, tuftelin 1
