Genetics

Front 1

What is in each DNA?

Back 1

DNA is packaged into 23 pairs of chromosomes in each cell except in the germ cells (X&Y or X&X) which have 23 SINGLE chromosomes.

Front 2

Where does each pair of chromosome come from?

Back 2

Once chromosomes for each pair comes from the individuals' mother and the other comes from the father.

Front 3

What are the four bases of DNA?

Back 3

A
T
G
C

C & G always pair up together
A & T always pair up together

Front 4

What chromosomal defect is a characteristic of Down Syndrome?

Back 4

There are three chromosomes on chromosome 21

Front 5

What are the maternal age risks when getting pregnant?

Back 5

Maternal Age 25 > Risk of Down's = 1 in 2500

Maternal Age 30 > Risk of Down's = 1 in 952

Maternal Age 35 > Risk of Down's = 1 in 378

Maternal Age 40 > Risk of Down's = 1 in 106

Front 6

What is Robertsonian translocation?

Back 6

Another way to get Down Syndrome in which the extra chromosome on 21 moves to the tip of chromosome 14.

Front 7

What is Klinefelter Syndrome?

Back 7

Its when a male karyotype with more than one X (XXY).

Approx. 1 in every 500 males.

S/S: reduced fertility, learning disabilities, hypogonadism; decreased muscle mass & strength; feminine distribution of adipose tissue; decreased physical endurance; osteoporosis

Front 8

What is a centromere?

Back 8

?

Front 9

What is mitosis?

Back 9

?

Front 10

What is meiosis?

Back 10

?

Front 11

What is 47 XYY?

Back 11

Its when there's an extra Y chromosome (eg: XYY)

About 1 in 1,000 ppl.

Usually no unusual physical features or medical problems and have normal sexual development & fertility.

S/S: taller than average, risk of learning disabilities & delayed speech & language skills; some behavioral problems but these characteristics vary widely.

Front 12

What is Turner Syndrome?

Back 12

Caused by a large collection of lymphatic fluid in back of neck that can not drain.

Most babies with Turner Syndrome are miscarried but if they survive then as a baby puffy feet and hands & neck is distended from fluids. As girls progress into womenhood, they are usually shorter & are infertile.

Front 13

What is reciprocal translocation?

Back 13

look at picture in slides

Front 14

What is Cri du chat Syndrome?

Back 14

Main characteristic as a baby is their cat like cry.

These children have severe retardation.

Front 15

What is DNA?

Back 15

Each cell has 46 human chromosomes = that is 23 pairs in each cell.

3 billion DNA subunits (the bases: A, T, C, G)

Approx. 30,000 genes code for proteins that perform nost life functions

each DNA molecule is half "old" & half "new"

Front 16

What is the start codon & what is the end codon?

Back 16

ATG = start codon (indicates the beginning of a DNA strand)

TAA, TAG, TGA = stop codon (indicates the end of a DNA strand)

Front 17

What is translation?

Back 17

?

Front 18

What is transcription?

Back 18

?

Front 19

What is Gene mutation?

Back 19

a mutation is an alteration in the code of a gene that may be or may not prevent the production of that gene's normal protein.

Front 20

What are types of mutations?

Back 20

1) Normal - eg: the sun was hot

2) Missense or subsitution - eg: the sun wBn hot

3) Frameshift -
eg: INSERTION ~ the suA nwa sho t
eg: DELETION ~ ths unw ash ot

Front 21

What are somatic mutations?

Back 21

Somatic mutations are passed on to successive generation of the cell (ie: all the daughter cells from then on has the mutation but they are not passed on to future offspring of the individual)

Front 22

How do genes & cancer interelate?

Back 22

Cancer results from a series of mutations that take place in genes that control the reproduction of the cell. Cells with such mutation reproduce themselves at a much more rapid rate.

Front 23

What are the 3 classes of cancer genes?

Back 23

1) Oncogenes - that positively regulate growth
2) Tumor suppresser genes - that negatively regulate growth
3) DNA Repair Genes -

Front 24

What are germline mutations?

Back 24

If a mutation occurs in a germ cell of an individual then it will cause mutations to any cells after fertilization to all somatic cells and approx. 1/2 of the germ cells of the new individual.

Therefore the cell mutations will be passed on to successive gerneations of that individual.

Front 25

What is an allele?

Back 25

An allele is a variant form of a gene at a particular locus location on a chromosome).

Different alleles produce variation in inherited characteristics such as hair color or blood type.

Front 26

What is the mendelian pattern or inheritance?

Back 26

Autosomal dominant

Autosomal recessive

X-linked recessive

X-linked dominant

Front 27

What is the CARDINAL features of hereditary cancer?

Back 27

Hereditary cancer is cancer in two or more close relatives.

Bilateral cancer in paired organs.

Early age onset.

Specific constellation of cancers that compose a known syndrome.

Medelian pattern of inheritance.

Front 28

What is Huntington Disease?

Back 28

Excessive number of CAG repeats in HD gene.

Its a disorder of mood, mentation, & movement.

Onset in middle adult years.

HD gene has virtually 100% penetrance.

No cure or effective treatment.

Onset in 40s; die within 10-15yrs. of diagnosis.

Front 29

What is autosomal recessive inheritance?

Back 29

Afftected individuals have mutations in both alleles of the gene pair.

Carriers of the mutations have a mutation in one of the alleles.

Front 30

What is Tay Sachs?

Back 30

Build-up of GM2 ganglioside in neuronal lysosomes results in hypotonia, the loss of developmental milestones, seizures, blindness, deafness and death by 4 or 5.

Front 31

What is sickle cell disease?

Back 31

A to T point mutation in Beta globin gene.

Heterozygote frequency of 1/12 among African-Americans.

Homozygotes have increased frequency of infectious disease, chronic anemia, painful sickle crises.

Front 32

What is the newborn screening?

Back 32

All newborns are screened.

Used to diagnose autosomal recessive disorders for which early treatment can make a difference.

Happens prior to discharge, repeat testing if before 24hrs, within first week.

Its used to help prevent illness, mental retardation and death.

Front 33

what is Phenylketonuria (PKU)?

Back 33

Very rare - 1 in 13,000 to 1 in 19,000.

Its an absence or deficiency of phenylalinine hydroxlase due to mutation in PAH gene.

Phenylketones in urine.

Genetic and clinical variability > 4000 mutation and most of those affected are compound heterozygotes.

Front 34

What is an example of x-linkied recessive disorders?

Back 34

Muscular Dystrophy - loss of muscle control.

One normal gene & one mutated gene.

Front 35

What is the fragile X mental retardation?

Back 35

X-linked dominant

2nd most common form of retardation due to genetics.

Characteristics: hyperextensible joints & large or prominent ears.