Exam 1- Genes And Genetic Disease Flashcards
Codon
Sequence of 3 nitrogenous bases that specifies a particular amino acid. Triplets of based.
Sequence of 3 nitrogenous bases that specifies a particular amino acid. Triplets of based.
Codon
Noncoding segment spliced out of mRNA
Intron
Segment of mRNA that codes for proteins
Exon
Alteration of DNA capable of being passed to offspring.
Missense _________
Nonsense _________
Frameshift _________
Mutation
Substance that alters genetic material (DNA)
Mutagen
Segment of DNA that is the basic unit of inheritance
Gene
Strand of condensed chromatin visible right before cell division. A somatic cell has 23 pairs of_______________. 1 sex_______________ and 22 nonsectarian_____________(autosomes)
Chromosome
Chromosome that is not a sex chromosome. 1 pair of sex chromosomes and 22 pairs of___________.
Autosome
Different version of a paired gene at a given locus.
If 2____________ are found together, the___________ that is observable is the dominant, and the one whose effects are hidden is recessive.
Dominant_____________: capital letter
Recessive: lowercase letter
Can be codominant
Ex: Hgb A vs Hgb S
Allele
A DNA mutation that involves an addition or deletion of a number of base pairs that is not a multiple of three, and thus alters all of the codons downstream from the site of insertion or deletion.
Frameshift mutation
Interchanging of genetic material between nonhomologous chromosome. One chromosome breaks and becomes part of another chromosome.
Type of chromosomal aberration/ alteration.
Ex: Philadelphia chromosomal____________. Increased chances of CML and ALL.
Translocation
Loci on a pair of chromosomes have identical genes (type O)
Homozygous
DD, dd affected or unaffected homozygous
A pair of chromosomes have different genes (Person/Type A and B genes mix and are different), that, when mixed are called this.
Dd affected or unaffected____________.
Heterozygous
One of the chromosomes in somatic cell has only one copy instead of 2 normal.
Monosomy
One of the chromosomes in somatic cell has 3 copies instead of the normal 2.
Trisomy
The genetic material
Genotype
Expression of genes
Phenotype
Diploid cell makes a copy of itself
Mitosis
The process by which haploid cells are formed from diploid
Meiosis
1) RNA polymerase binds to DNA promoter region
2) transcription
3) mRNA is spliced to remove noncoding sections
4) mRNA leaves the nucleus
5) translation
Steps of protein synthesis
Ex: Turner syndrome, Down syndrome, fragile X syndrome, klinfelter syndrome
Chromosomal disorder
A somatic cell that has 46 chromosomes in its nucleus
Diploid cell
Determined by one gene mutation. Autosomal dominant, autosomal recessive, or X-linked recessive.
Strongly determined by genes.
Ex: CF, hemophilia A, sickle cell
Single gene disorder
Disorder linked to X Chromosome
Y chromosome only carries a few genes, so most sex-linked traits are X-linked.
More often seen in males than female, because they only have 1 X chromosome.
Dominant (rare) or recessive.
X-linked disorders
Cells have 3 copies of each chromosome
Triploidy
Inactivated X chromosome that is seen in normal female cells.
Barr body
Has 23 chromosomes, one member of each pair. Will meet up with another _________ to make a diploid. Aka gamete.
Haploid cell
More sets of chromosomes. In multiples of 23. Incompatible with life. More than 2 copies of each chromosome.
Triploidy- 3 sets of 23 chromosomes
Tetraploidy- 4 sets (92 chromosomes)
Polyploidy
Error during meiosis or mitosis. Homologous chromosomes fail to separate normally. Results in aneuploidy.
Nondisjunction
_____________ have Rr so can still pass it on but don’t have the expressed trait.
Phenotypically normal. Carries disease causing alleles.
Have to have 2 recessive genes to have expressed trait (rr).
Carrier
XY- male
XX- female
1 pair of sex chromosomes and 22 of autosomes.
Sex chromosomes
Abnormal number of single chromosomes. Loss of chromosome (monosomy) material more serious than duplicate.
23 pairs usually. On one pair you’re missing one chromosome and only have 1 (monosomy). On another pair you have 2 from one parent, for a total of 3 instead of 2 (trisomy). Autosomal aneuploidy usually lethal, but Can survive with trisomy13, 18, and 21.
Sex chromosomal aneuploidy is not lethal (except for monosomy (X): Y chromosome has little genetic info and extra X chromosome is usually inactive (fragile X). Having 1 X is lethal.
Aneuploidy
3 copies of the 21st chromosome.
Nondisjunction in egg.
Linked with maternal age.
Intellectual disability, poor muscle tone, increases congenital heart defects, increased risk for Alzheimer’s after age 40.
Down Syndrome (Trisomy 21)
Broken chromosomes or loss in DNA in 1 chromosome can have serious effect.
Cri du chat Syndrome- deletion of long arm of chromosome 5. Microcephalic, low birth weight.
Chromosomal deletion
Multiple copies of DNA portion. Less serious than deletion. But when they have offspring, chromosomes don’t align and offspring can have issues.
Chromosomal duplication
Single-gene disorders
Diseases are rare. Very rare for two affected people with the dominant trait to produce offspring. Dd if they have one capital D, they are effected. Only need to inherit a D from 1 affected parent to get the disease.
Genotype of affected person: DD or Dd
Genotype of unaffected person: dd
Males and female equally likely.
One of the patents has to have the disease.
Heterozygous individuals pass it on to 50% of their offspring. Does not skip generations because there are no carriers.
75% chance to pass on (recurrence rate) if both parents Dd (affected):
25% DD homozygous affected
50% Dd heterozygous affected
25% dd homozygous unaffected
Phenotype: observable effect
Ex: achondroplasia, Huntingtons
Autosomal dominant disorders
Single gene disorder
Disease: A person must have 2 recessive alleles. Must receive a a recessive gene from each parent. (dd) to get the disease. non sex-linked (same in M and F).
Rare, but number of carriers can be high.
Usually in children not parents.
If both parents heterozygous carriers (Dd) 25% of passing it on (recurrence rate). 50% that offspring will be phenotypically normal and 25% genetically normal.
Example: CF
Chances increase with consanguineous mating between relatives.
Autosomal Recessive trait (d)
Sections of chromosome. Each_______ is responsible for different characteristics of a person. If same on both ________ in a chromosome pair, it’s homozygous. If different, heterozygous.
Locus