1st mini test ch 3 genetics Flashcards
1
Q
Describe the purpose and results of the Human Genome Project
A
- Revolutionized the way we understand DNA
- vastly increased knowledge about certain genetic links to disease
2
Q
structure of DNA
A
Double- helical structure composed of nucleotides
3
Q
nucleotide
A
pentose sugar molecule, a phosphate molecule, purine or pyrimidine nitrogen base
4
Q
nitrogen base
A
adenine, thymine, guanine, cytosine (A-T C-G)
5
Q
Transcription DNA → RNA
A
- DNA synthesizes RNA within the nucleus
- DNA used to make RNA, RNA is used to make proteins, proteins “run the show”
- RNA= mirror image of a DNA strand
- RNA= one strand
- RNA nitrogen bases = adenine and uracil, cytosine and guanine
6
Q
protein coding sequences =
A
exons, the portion of a gene that codes for amino acids.
-Only about 10% of genome
7
Q
sequences w no code
A
intron
8
Q
an average gene contains ____ nucleotide base pairs
A
3,000
9
Q
roll call lmaooooooOO
A
- base+base=bair pair
- 3 base pair=codon
- group of codons=genes
- codons code for=amino acids
- genes (group of codons) code for=proteins
10
Q
amino acids are the base of _____
A
proteins
11
Q
an average gene can code for 1,000 _______ _____
A
amino acids
12
Q
Within a gene, an arrangement of three specific nucleotide bases=
A
codon
13
Q
gene is the “recipe” for making a ____
A
protein
14
Q
genes and amino acids
A
ok basically amino acids are made from codons and genes are made up from a group of codons idk man
15
Q
Single nucelotide polymorphic (SNP)
A
- called pinpoint mutation
- mutation is one nuclide of a gene sequence
- normal nucleotide sequence may b ACTTG…but w this mutation, the sequence is ACTGG
- so one point is fucked up
16
Q
Defective gene
A
-ex: BRCA1, BRCA2 –>more likely to get breast cancer w these
17
Q
Defective whole chromosome
A
-ex: trisomy 21, extra 21 chromosome–>down syndrome
18
Q
Germ-cell mutation
A
mutated gamete (sperm and ovum) -can be inherited or sporadic
19
Q
Somatic cell mutation
A
(occurring in body cells) is not inherited
20
Q
mutations can be _____ or ______
A
inherited or sporadic (environmentally induced)
21
Q
Labeling a gene
A
- chromosome # or X/Y
- long (lower) arm =q
- short (upper) arm=p
- Region (including band and subband if applicable)
- EX:cystic fibrosis gene; 7q31.2 indicates the gene is found on the long arm of chromosome 7 in the region numbered 31.2
22
Q
Define Karyotype
A
appearance and number of chromosomes of an individual
-AKA an individuals “chromosome picture “
23
Q
explain the chromosomal makeup of the normal human karyotype
A
- 46 chromatids=23 chromosomes
- 22 pairs are somatic cell chromosomes (autosomes)
- 23rd pair includes the sex chromosomes
- Structure=2 chromatic strands connects by a centromere
- Corresponding genes on each chromatid=an allele
24
Q
homozygous v. heterozygos alleles
A
- Homozygous: both alleles on each corresponding chromosome are the same
- Heterozygous: the alleles on corresponding chromosomes are not the same
25
Dominant v Recessive traits
An allele can carry a dominant trait or recessive trait (brown eyes= dominant, blue eyes= recessive)
26
Phenotype v Genotype
- Phenotype: how the gene mix is manifested in the individual (a person has brown eyes)
- Genotype: the genetic makeup of a person ( a brown eyed person can have a B-B or a B-b genotype)
27
father
XY
28
mother
XX
29
Illustrate the pattern of inheritance for a sex-linked trait
- A female often carries a trait the male offspring expresses
- The Y chromosome (which is smaller) does not have an equal number of genes as the X chromosome
- Some genes on the X chromosome are unopposed by an allele on the Y so what is on the X is expressed
30
Penetrance and an example
ratio of how many persons with genotype have the phenotype; are the disorders symptoms clearly evident??
EX: a gene is highly penetrant if most people express a gene if they have it; if a woman has the BRCA gene, there is an 85% chance of getting breast cancer; this gene is highly penetrant
31
Expressivity and an example
a disorder can be expressed more or less severely in different individuals
-EX: a person may have a gene for familial hypercholesterolemia but can have a mild or severe form of the disease
32
Describe multifactorial inheritance
- A disease is caused by a combination of inherited susceptibility and environmental factors that trigger a disorder
- Diabetes or cancer are multifactorial genetic diseases; a genetic susceptibility and environmental triggers cause this disorder
33
Discuss alterations in DNA, including an example
- DNA can sometimes be repaired by the cell
- ->Damaged nitrogen base can be replaced
- DNA alterations or mutations are changes in nucleotide sequences, as well as deletions or insertions of nucleotides
- These changes can represent the change of base sequences in a codon, leading to a change in the protein structure
- EX: a nucleotide base substitution results in a different amino acid being included in hemoglobin formation, leading to the development of sickle cell anemia
34
Explain the role of genetics in the cause and suppression of cancer including: Oncogenes
- Activated oncogenes can be inherited or acquired
- When the cell that possesses this activated oncogene undergoes transcription, the RNA will carry defective message of the activated oncogene onto to the ribosomes
- The ribosomes will synthesize defective proteins called ONCOPROTEINS
- These oncoproteins will direct the cell to undergo uncontrolled proliferation, persistent mitotic divisions, or persistent cancerous growth, which is why activated oncogenes can be considered cancer causing genes
35
Explain the role of genetics in the cause and suppression of cancer including: Tumor suppressor genes
- These genes inhibit uncontrolled cellular mitosis and lead to persistent proliferation
- EX: p53 tumor suppressor gene, which stops the mitotic cell division cycle
- When defective, tumor suppressor genes do not suppress cancerous transformation of cells and cancer growth occurs uninhibited
-
36
Explain the role of genetics in the cause and suppression of cancer including: VIRUSES
-Another way that cancer occurs is through viral insertion of an oncogene
- EX: HPV inserts its DNA into the DNA of cervix cells. When activated, this DNA stimulates the abnormal growth cycle associated with cancer cells
- ->Additionally, it inhibits the action of p53
- ->This is the mechanism for the development of cervical cancer from HPV infection
37
Explain the role of genetics in the cause and suppression of cancer including: "KNUDSON's "two hit" hypothesis:
- pair of alleles make up an individuals genotype--> if one of the alley of a pair becomes damaged or mutated, the normal corresponding allele can counteract and stop the effect in most cases
- ->the initial allelic mutation is the "first hit"
- In Knudson's investigation, he noticed that caner ONLY developed in persons who acquired a 2nd allelic mutation!!!!
- People who developed cancer possessed a hereditary mutation on one allele and acquired a second mutation on their normal allele sometime in the course of their lifetime = second “hit”
38
Aneuploidy
abnormal number of chromosomes
| -EX: trisomy 21
39
Translocation
occurs when a piece of one chromosome breaks off and attaches to another chromosome
40
Deletion
is part of a chromosome or a sequence of DNA is lost during DNA replication
41
Mosaic
occurs when there are cells with different numbers of chromosomes within the same individual
EX: some cells have 47. XXX and others have 45, X
42
Explain the purpose of a Genograms
Genograms can be used in genetic research to identify traits that are passed from one generation to another.
43
Cystic fibrosis
- autosomal recessive, if both parents are carriers, 25% chance of having the condition
- increased mucus in lungs and pancreas; significantly affects function of both
- testing: newborn screening required in the US; genetic testing of parents if family history
44
Marfan syndrome
- autosomal dominant; 50% chance of child having condition if one parent is affected
- connective tissue disorder; tall stature; heart structural abnormalities
- genetic testing; family planning counseling if family history
45
Tay Sachs disease
- autosomal recessive, if both parents are carriers, 25% chance of child having condition
- nervous system development affected; death often by age 3
- prenatal diagnosis; genetic testing of parents if family history
46
Turner Syndrome
- chromosomal abnormality; complete or partially missing X chromosome in females
- hypogonadism, short stature, webbing of neck, often unable to reproduce
- prenatal diagnosis- amniocentesis or chorionic villus sampling
47
klinefelter syndrome
- chromosomal abnormality in males; 1 in 500-1000 males; 47XXY
- lack of testes development, decreased cognitive development
- prenatal diagnosis; many not be detected until adolescence
48
Down Syndrome
- most common chromosomal disorder in humans, trisomy 21; 1 in 800 live births; risk increases with maternal age
- changes in facial structure, neurologic development issues, cardiac abnormalities
- prenatal screening
49
Fragile X syndrome
- disorder of the X chromosome; 1 in 1500-1800 males and females respectively
- affects neurological development
- moleculer genetic testing to determine extent of X chromosome abnormality
50
Huntington Disease
- autosomal dominant; 50% chance of child having condition if one parent affected
- neurological disorder with adult-onset;
- genetic testing; condition may be passed onto offspring before parent displays characteristic associated with the condition
