BSC Genetics

Question 1

define gene

Answer 1

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

Question 2

define mutation

Answer 2

genetic disorders caused by 1+ changes, preventing the gene from functioning properly
- allelic variants that are associate w/ disease

Question 3

define locus

Answer 3

physical location of a gene

Question 4

define allele. how many copies do humans have

Answer 4

different versions of genes such as eye color brown vs blue
- 2 copies of all autosomal genes

Question 5

what is the DNA molecule composed of

Answer 5

5C sugar (deoxyribose)
phosphate molecule
nitrogen base (A,C,G,T)

Question 6

what is the central dogma

Answer 6

replication, transcription, and translation
DNA to mRNA through transcription, and mRNA to protein through translation

Question 7

define codon

Answer 7

building block of proteins, code for AAs
- start codon is AUG stop codon UAA, UAG, UGA

Question 8

what is the anti-codon

Answer 8

complementary RNA code that tRNA has

Question 9

describe each section of 7q21.13 locus

Answer 9

chromosome 7
q arm
21 band
13 subband

Question 10

what is a polymorphism

Answer 10

allelic variant not associated w/ disease

Question 11

what are the 2 types of mutations and what are examples of each

Answer 11

gene (point, frameshift, and in-frame)
chromosome (deletion, insertion, inversion, duplication and translocation)

Question 12

define point mutation and describe

Answer 12

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

Question 13

define frameshift and in-frame mutation and describe

Answer 13

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

Question 14

define phenotype

Answer 14

measurable trait such as eye color or height

Question 15

define genotype

Answer 15

genetic makeup of an organism at a single locus

Question 16

define proband

Answer 16

person who brought attention to medical prof. about disease, may not be where disease actually began

Question 17

define Mendelian disorders

Answer 17

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

Question 18

describe autosomal dominant inheritance

Answer 18

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

Question 19

describe huntington disease

Answer 19

defective gene on chromosome 4, frameshift mutation, includes chorea (jerky random movements, decline in thinking, mood changes)

Question 20

describe autosomal recessive inheritance

Answer 20

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

Question 21

what are examples of autosomal recessive inheritance

Answer 21

sickle cell disease (anemia) and cystic fibrosis
- observed more frequently in consanguineous relationships

Question 22

describe sickle cell disease

Answer 22

• 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

Question 23

describe x- linked dominant inheritance and an example

Answer 23

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

Question 24

describe fragile x syndrome

Answer 24

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

Question 25

describe x- linked recessive inheritance and an example

Answer 25

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

Question 26

describe hemophilia A

Answer 26

factor BIII deficiency b/c mutations point and frameshift occur in this gene at Xq28
- get blood clotting factors infused

Question 27

what is complex inheritance

Answer 27

interactions of variations in multiple genes and environmental factors
- include heart disease, diabetes, and asthma

Question 28

what are the 5 chromosome mutations

Answer 28

1) duplication
2) inversion
3) deletion
4) insertion
5) translocation

Question 29

which gene has an impact on periodontal disease? what tests can we run to assess caries/ periodontal disease

Answer 29

• 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

Question 30

which genes are believed to impact caries

Answer 30

ameloblastin, aquaporin 5, enamelin, mucin 5, tuftelin 1