Intro 7/30

Question 1

One DNA Double Helix

Answer 1

One chromosom,e (before replication

Question 2

karyotype

Answer 2

the number and visual appearance of the chromosomes in the cell nuclei of an organism;
lymphocyte B cell DNA are used in humans

Question 3

Dosage of a gene

Answer 3

is the number of copies of a particular gene present in a genome (one chromosome line is one dosage. Homologous chromosomes have a gene dosage of 2)

Question 4

Colchicine

Answer 4

inhibits microtubule polymerization by binding to tubulin. Spindle poison. Used in karyotyping to keep sister chromatids together in metaphase

Question 5

Giemsa-trypsin

Answer 5

Dye and protease used in karyotyping. Trypsin digests proteins (histones) to isolate DNA. Stain dyes DNA- banding pattern on chromosomes.

Question 6

Types of genetic diseases

Answer 6

chromosome disorders, single gene disorders, mitochondrial disorders, multifactorial disorders

Question 7

Chromosomal disorders

Answer 7

abnormalities in the number or structure of chromosomes (i.e. too many genes, too few genes, altered genes) Polyploidy, aneuploidy, insertion, deletions, translocations

Question 8

Polyploidy

Answer 8

in humans, having a multiple of 23 total chromosomes, common in cancers

Question 9

Aneuploidy

Answer 9

1 extra chromosome overall

Question 10

single gene disorders

Answer 10

alterations in the coding sequence produce effects on the function of the protein (usually loss, but can be gain or alteration of function)

• DNA coding for mRNA but also tRNA, rRNA, snRNA, miRNA
• Autosomal disorders and sex-linked disorders

Question 11

Mitochondrial genome contains 13 genes that encode for

Answer 11

Electron transport chain (production of ATP)

Question 12

Mitochondrial disorders

Answer 12

maternal inheritance for mutations in mitochondrial DNA

can have same mutations as on chromosomal disorders

Question 13

multifactorial disorders

Answer 13

most common of genetics disorders and probably diseases

combo of both genes and the environment: polygenic, teratogenic, multifactorial

Question 14

Polygenic

Answer 14

many genes acting together

Question 15

Teratogens

Answer 15

chemicals in the environment that cause developmental deformities in babies.

Question 16

Chronic myelogenous leukemia

Answer 16

inherited leukemia. Caused by Chromosome 22/chromosome 9 translocation. Causes fusion of Bcr/Abl portions of genes. (called Philadelphia chromosome)

Question 17

Tools for genetic diagnosis

Answer 17

inheritance patterns (autosomal or sex-linked: pedigree), chromosome analysis (karyotyping, FISH, CGH), biochemical tests (plasma amino acids, urine organic acids), DNA diagnostic tests (whole genome sequencing)

Question 18

Autosomal dominant pedigree

Answer 18

somebody is affected every generation

both males and females are affected

Question 19

Karyotyping

Answer 19

detects alteration in number: large duplication/deletions, translocations

Question 20

FISH (fluorescent in-situ hybridization)

Answer 20

used to check specific DNA sequence portion of known diseases. Performed on cells frozen in metaphase. Fluoresces target gene after the cell is washed and is hybridized by the tagged single strand DNA sequence
-if the probe hybridized to the sample, the DNA sequence is present (ex. Williams syndrome. Chromosome 7 band present in one chromosome). -tests for deletions and duplications

Question 21

CGH (comparative genomic hybridization) AKA Chromosomal microarray

Answer 21

• checks for deletions/insertions (duplications) in genome
• the DNA of the patient is compared to a reference DNA of a healthy person
• metaphase slide is prepared and frozen, DNA is removed, chromosomes are fluoresced.
• patient DNA is green
• Reference/control DNA is red
• If red on array plate- this portion of DNA is deleted in the Patient
• if Green on array plate, this portion of DNA is duplicated
• if yellow, the DNA sequence of the certain part is the same as the control DNA
• ex. Williams syndrome. Chromosome 7 band present in one chromosome

Question 22

Plasma amino acid test

Answer 22

can detect Phenylketonuria (loss of PAH activity resulting in accumulation of phenylalanine)

Question 23

Presymptomatic testing

Answer 23

testing a person for a genetic mutation that will CERTAINLY cause a disease later in life (i.e. Huntington’s disease and familiar adenomatous colon cancer)

Question 24

Predisposition testing

Answer 24

testing a person for a genetic mutation which MIGHT cause a disease later in life

Question 25

Mosaicism

Answer 25

more than one genotype in a person

Question 26

Mitochondrial inheritance

Answer 26

abnormal mitochondria passed on in the cytoplasm of an ovum from mother

Question 27

Genetic imprinting

Answer 27

parent-of-origin difference in gene expression

Question 28

Uniparental disomy

Answer 28

both chromosomes of a pair inherited from one parent

Question 29

Unstable triplet repeat mutations

Answer 29

develop by expansion of normally present trinucleotide repeats