Basics of genetic inheritance

Question 1

Definition of genotypes

Answer 1

The genetic constitution of an organism

Question 2

Definition of monogenic

Answer 2

Associated with 1 gene

Question 3

Definition of polygenic

Answer 3

Associated with many genes

Question 4

Definition of pharmacogenics

Answer 4

Patient’s genotype dictates prescribed drugs (personalized medicine)

Question 5

Definition of genes

Answer 5

Discrete units of inheritance, distributed across chromosomes
Composed of DNA found around histones

Question 6

Definition of chromatin

Answer 6

DNA+ protein=chromatin

Question 7

Definition of karyotype

Answer 7

An individual collection of chromosmes

Question 8

Definition of autosomal

Answer 8

Not a sex chromosome

Question 9

Definition of G banding

Answer 9

Alternate light and dark bands, each chromosome pair has characteristic pattern

Question 10

Definition of cytogenetics

Answer 10

Study of the genetic compound of a cell through visualization, analysis of chromosomes

Question 11

Definition of metacentric

Answer 11

Centromere in center of chromosome

Question 12

Definition of submetacentric

Answer 12

Centromere not in center of chromosome

Question 13

Definition of acrocentric

Answer 13

Centromere just under stalk and satellite of chromosome

Question 14

Definition of pseudoautosomal

Answer 14

Present on sex chromosomes but inherited in an autosomal way

Question 15

Definition of heterochromatin

Answer 15

Condensed DNA, genetically inactive

Question 16

Definition of euchromatin

Answer 16

Loosely packed chromatin, genetically active

Question 17

Definition of aneuploidy

Answer 17

Irregular no of chromosomes, caused by non disjunction

Question 18

Definition of trisomy

Answer 18

3 copies of a chromosome

Question 19

Definition of monosomy

Answer 19

1 copy of a chromosome

Question 20

Definition of euploidy

Answer 20

complete chromosome set

Question 21

Definition of non disjunction

Answer 21

Failure of homologous chromosomes to separate properly during meiosis, inaccurate segregation

Question 22

Definition of locus

Answer 22

Chromosomal location

Question 23

Definition of allele

Answer 23

Variant of a gene

Question 24

Definition of recessive

Answer 24

Phenotype of allele can be masked

Question 25

Definition of dominant

Answer 25

Phenotype masks recessive allele

Question 26

Definition of homozygous

Answer 26

2 of the same allele

Question 27

Definition of heterozygous

Answer 27

2 different alleles

Question 28

Definition of multifactorial

Answer 28

Influenced by genes and environment

Question 29

Definition of wild type allele

Answer 29

The most common form of an allele that has not mutated

Question 30

``` Structure of genes in DNA with widths DNA double helix Chromatin Nucleosome Extended chromosome Condensed chromosome ```

Answer 30

``` 2nm DNA double helix 11nm Chromatin = DNA + histones 30nm Nucleosome 300nm Extended section of chromosome 700nm Condensed section of chromosome ```

Question 31

What is the human karyotype How do you study it What is the nomenclature used for a euploid male and female

Answer 31

Individual's set of chromosomes (23 pairs) 22 autosomal, 1 sex pair Studied in cytogenetics, giemsa stain => G banding 46XX, 46XY

Question 32

What are the 3 properties that differentiate different chromosomes

Answer 32

Size G band pattern Centromere location and arm length (pq) - metacentric - submetacentric - acrocentric

Question 33

Importance of replicating chromosomes and method of replication

Answer 33

Development, growth, replace lost cells in mitosis Transmission of genetic info to offspring, meiosis

Question 34

Describe the steps of mitosis - Interphase - Prophase - Metaphase - Anaphase - Telophase and cytokinesis What is the result?

Answer 34

Interphase -Duplication Prophase -Condensation Metaphase -Line up on equator Anaphase -Pulled apart at centromere Telophase and cytokinesis -Cytoplasm pinches => 2 diploid daughter clones

Question 35

Describe the steps of meiosis - Interphase - Prophase I - Metaphase I - Anaphase I - Prophase II - Metaphase II - Anaphase II - Telophase and cytokinesis What is the result

Answer 35

Interphase -Duplication Prophase I -Condensation, homologous chromosomes crossover Metaphase I -Pairs line up on equator Anaphase I -Pairs separated but chromatids stay together Prophase II -2 daughter cells Metaphase II -Sister chromatids line up on equator Anaphase II -Sister chromatids separate Telophase and cytokinesis -4 genetically unique granddaughter haploid

Question 36

Describe the relative sizes of the sperm and egg and why

Answer 36

4 eggs => 1 egg, cytoplasm merges to maximize survival Egg > sperm

Question 37

What defines maleness on the Y chromosome When can someone show male characteristics with XX? When can someone show female characteristics with XY?

Answer 37

SRY = defines maleness (testes determining factor) Found in MSY with euchromatin and heterochromatin SRY in XX No SRY in XY

Question 38

What percentage of aneuploidies/trisomies end in spontaneous aborton What aneuploidies result in viable offspring and why

Answer 38

50% ``` Downs = 21 (characterized by simian crease) Patau = 13 Edward = 18 ``` ``` Klinefelter = XXY 47 XYY = XYY 47 Turners = X 45 ```

Question 39

What are the 2 laws in Mendelian inheritance

Answer 39

Law of segregation | Law of independent assortment

Question 40

Describe the inheritance pattern of CF What chromosome is affected What advantage do carriers have

Answer 40

Autosomal recessive CFTCR on chromosome 7 Hidden in heterozygous carriers, frequency high if there is a selective advantage Not sex linked, infrequent

Question 41

Describe the inheritance pattern of HD | What chromosome is affected

Answer 41

Autosomal dominant HD CAG stutter on chromosome 4 Frequent Not sex linked

Question 42

Describe the inheritance pattern of Hemophilia A Why does this affect different sexes differently

Answer 42

X linked recessive Affects F7 Males only have 1 X, only 1 recessive allele needed to express HA Mother => child transmission only Sons affected more than daughters

Question 43

What are the properties of complex disorders | What are the 2 types of traits that can arise as a result?

Answer 43

Polygenic, multifactorial Traits can be - discontinuous - continuous

Question 44

How would you assess the genetic and environmental contribution of a polygenic complex disease?

Answer 44

More frequent in MZ => genetics | More frequent in DZ => environment