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51 Cards in this Set

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What are the five major types of genetic disorders?
Single gene
mitochondrial
polygenic/multifactorial
chromosomal
somatic cell
What is the 2 hit hypothesis?
Cancer requires mutations in at least 2 genes. One hit may be inherited already in genes passed generation to generation. In this instance cancer will only require one hit.
What is Mendels first law?
For any given train, progeny inherit 2 alleles, one from each parent. Interaction between these alleles determines the trait.
Each parent randomly passes on one of these alleles to their offspring.
Segment of DNA that encodes a specific protein
Gene
Physical region on a chromosome that has DNA that contains a specific gene
Locus
Alternative forms of a gene that differ in sequence
Alleles
What is Mendel's 2nd law?
Law of Independent Assortment - alleles of genes at 2 different loci segregate independently from one another
What is the exception to mendel's 2nd law?
It is not true for genes that lie close to one another, genes can be inherited in blocks together.
What is a chromosome?
single molecules of DNA complexed with proteins that carry our genes. 46 total, 23 pairs.
How many gene segregation events are needed in the human?
Only 23, instead of thousands, thanks to chromosomes.
Non gamete forming cells that are diploid
Somatic cells
Cells responsible for production of gametes
germline cells
Sperm and ova, haploid cells
Gametes
Fustion of 2 gametes, diploid
Zygote
2 copies of each chromosome, 46 in humans
Diploid
one copy pf each chromosome
haploid
paired chromosome during meisosi, one from each parent, that are not identical but only a few base pairs different
Homologous chromosomes
2 identical duplicated chromosomes joined by a centromere
sister chromatids
ploidy
the number of copies of chromosomes - haploid, diploid, tetraploid
Aneuploid
Any number of chromosomes that is not an exact multple of haploid number, ie not a multiple of 23, like trisomy and monosomy
Synapse occurs during what stage of meiosis
prophase 1, forming bivalent tetrads
at what stage do precursor oocytes mature to?
metaphase I of meiosis
When are recombinases expressed
During synapsis of prophase I, catalyzing reciprocal exchange of parts of one chromosome for another, ie crossing over
Histones
chromosomes wrap DNA material around these for protection
Histones further into these units
Nucleosomes
This DNA conformation is seen when cell is not dividing
Extended conformation
Each molecule is approximately 10 million base pairs
DNA
Two rings, A or G
Purine
One ring, T or C
Pyramidine
Why is DNA semi-conservative?
Each resulting molecule from replication contains one new strand and one old strand
What causes disease in genetic disorders?
Changes in protein level/activity. Changes in DNA lead to changes in proteins.
A region of DNA that specifies a trait
Gene
ONE GENE
ONE PROTEIN*

*There are some genes that encode RNA that is not transcribed
4 Basic Elements of a Gene
Promoter, Coding Sequences, Intervening sequences, Structural regions
Controls amount of mRNA produced
Promoter
Gets transcribed into proteins
Coding sequence, Exon
Gets spliced out of mRNA
Intervening sequence, Intron
Contains promoter and untranscribed 5' and 3' regions
Structural region
The site where RNA polymerase binds, thus determining trascriptional start site a specified number of bases from the TATA box
Basal promoter
Help control access to polymerase binding site
Enhancers and Tissue Specific Elements
In mRNA - it's U instead of what?
T
RNA polymerase can bind to promoter of any gene unless the site is occupied by a repressory
Open conformation transcriptional control, as seen in prokaryotes
In order for RNA polymerase to bind, activators must bind to enhancer site within the promoter and unwind DNA by phosphorylating or acetylating the histones
Eukaryotic transcriptional control
What three things must be done before mRNA is ready to go?
Introns spliced out, polyadenylation, and capping.
Mutations at this point are especially severe
At splice junctions. It will allow intons to remains in mature RNA and disrupt all following processes.
The translational start site
AUG - encoding methionine
3 bases read by ribosome at one time, producing amino acids to add to polypeptide chain
Codon
Codons are read by this substance that transfers a specific AA to it's "anti-codon" message
tRNA
How many binding sites for tRNA do ribosomes have?
2
Translation does not yield this
An active protein. It must be folded and placed with other peptides to become fully active.
Cleavage, lipidation, phosphorylation, glycosylation, and sulfation are all forms of this
Post-translational modification of a protein