5 Mendelian inheritance

Question 1

Autosome

Answer 1

chromosomes that are not considered sex chromosomes

Question 2

Allosome (gonosome)

Answer 2

sex chromosomes (X and Y)

Question 3

Gametes

Answer 3

Sex cells,

contain one copy of each chromosome and either X or Y

Question 4

Haploid

Answer 4

cells having one copy of each chromosome

Question 5

Diploid

Answer 5

cells having two copies of each chromosomes

Question 6

Allele

Answer 6

a form of a gene.

Question 7

Polymorphism

Answer 7

when a locus has multiple alleles present at one locus

Question 8

Hemizygous

Answer 8

One allele, example x linked genes in males

Question 9

Pleiotropism

Answer 9

A single mutant gene results in many phenotypes.

A single disease causing mutation affects multiple organ systems.

Question 10

Occulodentodigital Dysplasia (ODD)

Answer 10

Connexin mutation ( one gene). form of pleiotropism

Clinical features: thin nose, microcephaly, micropthalmia, microcornea, microdontia, partial adontia, hand and foot abnormalities

Question 11

Incomplete dominance

Answer 11

expression of two different alleles results in an intermediate phenotype. (Red + white = pink is expressed)

Question 12

Codominant

Answer 12

Each allele results in an observable phenotype

ex. blood type- both AB are expressed.

Question 13

haploinsufficiency

Answer 13

Normal physiology contains more than half of full functioning gene PRODUCT. Need more than one gene.

affected individuals do not have affected parents.

Resulting form new mutation (in sex cells)

Question 14

Penetrance

Answer 14

How frequently the allele expresses itself phenotypically

50% penetrance= 50% of people carrying allele will express trait.

Question 15

X-linked disorders

Answer 15

Most are X-linked recessive (all males express it)

Question 16

X inactivation

Answer 16

One X chromosome in all females is inactive. Random process 50/50 maternal or paternal.

Inactive one is targeted by noncoding RNA. Recruits chromatin remodeling machinery > heterochromatic > gene regions methylated > Barr body

Dependent- once inactivated every daughter cell will have the same X chromosome inactivated.

Incomplete- some genes from inactivated X can ‘leak out’

Question 17

Genetic Mosaicism

Answer 17

cells with different genotypes or chromosome constitutions are present in one individual

Due to X inactivation.

Question 18

Types of problems related to gene inheritance

Answer 18

Enzymes defects- build up of substrates, inhibition of pathways, failure to inactivate damaging substrates

Receptors- wrong concentration, altered signaling

Non enzyme- changes in carriers and structural proteins

Adverse reaction to drugs- drug metabolizing enzymes, transporters, and receptors.

Question 19

Myotonic Dystrophy

Answer 19

Autosomal dominant condition with variable expression of clinical severity and age of onset.

ex. grandma has cataracts no face weakness, mom developed face weakness cataracts later in life, son congenital and severe case.

Due to expressivity- genes can express differently within the same genotype.

Question 20

How is incomplete penetrance different from variable expression?

Answer 20

incomplete penetrance- Some individuals have disease genotype but do not display the phenotype

Variable expression- shows different degrees of phenotype.

Question 21

Locus Hetorogeneity

Answer 21

single disorder caused by mutations at different loci.

Question 22

New mutation

Answer 22

passed form unaffected parent to offspring.

Must be a gremline mutation to pass on. would occur during cell proliferation stage of somatic cells or in sex cells.

Often high mortality and infertility rates.

Question 23

Missense mutation

Answer 23

Alters meaning of sequence so that it codes for a different amino acid.

May or may not affect overall protein structure.

Question 24

Nonsense

Answer 24

Alters meaning of the code to stop codon

Truncated protein.

Question 25

Framehsift

Answer 25

insertion or deletion in sequence.

Everything down stream will be changed (unless multiple of three)

Question 26

Trinucleotide repeats mutations

Answer 26

Some repeats are important for cell length and how it is read.

can lead to disease if mutated
ex. form of epilepsy, fragile x syndrome, ataxia, hunting tons disease, myotonic dystrophy