Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
70 Cards in this Set
- Front
- Back
|
What is the "p" arm?
|
The short arm of the chromosome
|
|
|
What is the "q" arm?
|
The long arm of the chromosome
|
|
|
What is a karyotype?
|
When organized, shows arranged chromosome pairs
|
|
|
What are the three centromere locations in chromosome?
|
Metacentric: approximately centered.
Sebmetacentric: Slightly away from the center. Acrocentric: Centromere near an end. |
|
|
What is a barbody?
|
Dosage compensation of x-linked genes.
"turns off" the second x chromosome very early in development. Highly condensed DNA. Covers and coats the gene so that it can't be expressed. |
|
|
What does mosaic females mean?
|
some cells express the paternal chromosome.
Other cells express the maternal chromosome. Ex: Calico cats |
|
|
What is pseudoautosomal inheritance?
|
Shows autosomal inheritance patterns
Regions of homology: active genes at tips. Different levels of expression across chromosomes. Show autosomal inheritance patterns even though located on X chromosome. |
|
|
How can human history be traced through Y-chromosome haplotype?
|
Y chromosome undergoes essentially no recombination.
is inherited unchanged from generation to generation UNLESS mutation occurs. SSPs are ideal for distinguishing haplotypes. Haplotypes that share many alleles have more recent common ancestral Y chromosome. EX: Genghis Khan, Lemba of South Africa, and European Gypsies. |
|
|
What is Euploid?
|
Chromosome number that is viewed as the normal number.
23 diploid pairs in humans |
|
|
How do chromosomal abnormalities occur?
|
Errors in division.
Ex: nondisjunction |
|
|
What is polyploid?
|
"many sets"
3 or more sets of chromosomes. Occurs mostly in plants |
|
|
What is aneuploidy?
|
Alteration in number of paticular chromosomes.
2n+/-1 |
|
|
What is trisomic?
|
A third copy of a particular chromosome.
Ex: Trisomy 21, Downs Syndrome |
|
|
What is monosomic?
|
Missing one of normal copies of a chromosome.
|
|
|
What is a chromosome deletion?
|
Whole segment of the chromosome is missing.
Less dosage. |
|
|
What is a chromosome duplication?
|
Additions to the chromosome.
Increase in dosage. |
|
|
What is a chromosome inversion?
|
Change in direction along a single chromosome.
|
|
|
What is a chromosome translocation?
|
One segment becomes attached to another chromosome.
Simple of reciprocal. Reciprocal translocation= exchange |
|
|
What is ectopic recombination?
|
Occurs within a chromosome rather than between.
Repeated DNA sequences within the DNA can undergo pairing and homologous recombination. Deletion of regions in between the repeats will occur. |
|
|
What are tandem duplications?
|
Segments of repeated DNA in the same orientation and directly next to the normal region.
Unequal crossing over can lead to an increase or decrease in the number of repeats. |
|
|
What is a paracentric inversion?
|
The centromere is not included in the inverted region.
Crossing over in a paracentric inversion creates dicentric and acentric chromosomes. |
|
|
What are translocations?
|
Aberrant exchanges of parts between nonhomologous chromosomes
|
|
|
What is a robertsonian translocation?
|
Nonreciprocal translocation.
Two nonhomologous acrocentric chromosomes undergo fusion of their short arms. |
|
|
What is the position effect?
|
Repositioning of genes affects its level of expression or in some cases its ability to function.
Loss of function can occur when a gene is moved from an area of euchromatin to an area of heterochromatin. |
|
|
What is PEV?
|
Mottled phenotype resulting from patches of wt cells and patches of cells with an inactivated gene.
|
|
|
What is binary fission
|
How bacetrial cells reproduce.
Except when a mutation occurs, each daughter cells contains an identical copy of the mother cells' genetic material. |
|
|
What are the two causes of genetic diversity in bacteria?
|
1. New mutations can occur that alter the bacterial genome and affects the traits of bacterial cells.
2. Genetic transfer: genetic material is transferred from one bacterial cell to another. |
|
|
What are plasmids?
|
Nonessential DNA molecules that exsist outside the genome.
Not required from growth but usually provide some sort of growth advantage. Replicate independently of genome but rely on replication machinery of cell. |
|
|
What are f-factors?
|
Plasmids that carry several genes required for conjugation and also may carry genes that confer a growth advantage.
Anti-biotic resistence. |
|
|
Explain transfer of the F plasmid.
|
Contact is made between F Factor + and F Factor - cells through sex pili.
Once contact is made, the pili shorten, drawing the donor and recipient cells closer together. One strand of F-Factor is cut, then transferred, other strand stays in donor. Both strangs repicate so that the donor and recipient now have complete double stranded F Factor. |
|
|
What are Transposons?
|
DNA sequences that can move to new postions in the DNA.
Contain an insertion sequence that includes a tranposase gene flanked by inverted repeats and a few other genes that control transposition. Many transposons also contain antibiotic resistence genes. Can transfer between plasmids and genomes. |
|
|
What is an integron?
|
A DNA element that encodes a recombinase and sequences recognized by that recombinase.
|
|
|
What is a cassette?
|
A circular antibiotic-resistance coding region flanked by recombinase recognition sequences.
Recombined into integron, which provides promotor for expression of resitance genes in cassette. |
|
|
What is transformation?
|
DNA is released from a dead bacterium into the environment and is taken up by another bacteria, that then incorporates the DNA into its chromosome.
involves binding of DNA to the baterial cell surface, the uptake of DNA, and the incorporation of importated DNA into the bacterial chromosome via homologous recombination. Must have competent cell because they have special proteins that allow for transformation |
|
|
What is conjugation?
|
Direct physical contact transfers genetic material from donor to recipient cell
Bacterial sex Does not transfer whole chromosomes because the physical connection ends before all plasmid genes can be transferred. |
|
|
What is transduction?
|
A virus unintentionally transfers genetic information from one baterium to another.
|
|
|
What is a bacteriophage?
|
A virus that infects bacteria.
|
|
|
What is the lytic cycle?
|
Phage DNA directs synthesis of materials for many new phages.
Bacterial cell is lysed when new phages are released. |
|
|
What is the lysogenic cycle?
|
Phage DNA integrates into host chromosome.
Integrated phage DNA is replicated every time bacterial cell replicates. No new phage particles are made, bacterial cell is not lysed. |
|
|
What is cotransduction?
|
Genes close together in bacterial genome will be more likely to be transduced together on one fragment.
Cotransduction can be related to map distance in minutes. = 2-@x (cotransduct. frequency) ^1/3 |
|
|
What is transcription?
|
Produces an RNA copy or transcript of a gene.
Structural genes produce messenger RNA that specifies the amino acid sequence of a polypeptide. Carries into to make a protein |
|
|
What is translation?
|
Process of synthesizing specific polypeptide on a ribosome using an RNA sequence.
Eukaryotes have additional intervening step called RNA procesing where pre-mRNA is processed into functionally active mRNA. |
|
|
What is the ccentral dogma of gene expression?
|
DNA--> RNA--> protein
|
|
|
What is the structure of an amino acid?
|
Central carbon, amino group, carboxyl group.
Only the R group changes, which determines the structure and unique properties of each amino acid. |
|
|
In which direction to we read DNA
|
3' --> 5'
|
|
|
What is a transcription bubble?
|
Where the DNA opens up during transcription so that it can serve as a template for RNA synthesis.
|
|
|
Why aren't transcription and translation coupled?
|
Because they happen in different places.
|
|
|
What is rRNA?
|
Ribosomal RNA
structurally part of the ribosomes. |
|
|
What is mRNA?
|
Messenger RNA
Carries coding information to the ribosomes. |
|
|
What is tRNA?
|
Transfer RNA
transfers a specific active amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation |
|
|
What are promoters?
|
Set direction and start point of transcription
Can influence rates of transcription |
|
|
Explain the stages of transcription.
|
1. Promotor recognition (recognize that there is a gene)
2. Chain initiation: RNA polymerase bings to intiate transcription 3. Chain elongation: Only the template strand is transcribed, the transcription bubble is about 15 nt long with 8-9 nt paired 4. Termination: RNA polymerase reaches a terminator sequence at the 5' end and the RNA and polymerase are released-- usually requires a protein Rho. |
|
|
What is 5' capping?
|
Addition of 7-methylguanosine at the 5' end
Needed for exit of mRNA from nucleus and ribosome binding. |
|
|
What is splicing?
|
remolval of intron and joining of exons.
|
|
|
What are introns?
|
Intervening sequences
Transcribed but not translated Sections of DNA that will be removed. |
|
|
What are exons?
|
Coding sequences found in mature mRNA, will be transcribed and translated.
After introns are removed, these will be put together. |
|
|
Explain a polyA tail
|
3' polyadenylation
A bunch of adenines are added in (about 200 nt) increases stability, lifespan of the cytosol |
|
|
What is alternative spicing?
|
Single gene can encode multiple polypeptides by varying which exons are combined.
Can create alternative strands from the same starting strand. Explain more complecity from less genes. |
|
|
What are the principal components of translation?
|
mRNA
Ribosomes tRNA Aminoacyl rTNA synthetase Initiation, elongation, and release factors |
|
|
Explain the structure of a ribosome
|
Has discrete sites for tRNA binding and polypeptide synthesis.
P site: peptidyl site A site: aminoacyl site E site: exit site |
|
|
What is the genetic code?
|
Sequence of bases in an mRNA molecule
Reads in groups of three nt bases (called codons) |
|
|
Explain what degenerate means, in terms of the genetic code.
|
More than one codon an specify the same amino acid.
|
|
|
What is the Wobble effect?
|
The idetity of the third nucleotide in a codon is not always important.
Anticodon always forms usual base pairs with the first two bases but the last base is less confined, non-standard base pairs can form. |
|
|
What are the stages of translation?
|
1. Initiation: mRNA, first tRNA, and the ribosomal subunits assemble.
2. Elongation: Protein synthesis from start codon to stop codon. 3. Termination: Complex disassembles at stop codon, releasing completed polypeptide. |
|
|
Explain Initiation (translation)
|
Always begins at the 5' cap.
the initiation factors, the initiator tRNA, and small ribosomal subunits bind. Scans mRNA for first AUG codon. |
|
|
Explain Elongation (translation)
|
1. Aminoacyl tRNA brings a new amino acid to the A site.
2. A peptide bond is formed between the amino acid at the A site and the growing polypeptide chain. 3. Movement of the ribosome toward the 3' end of the mRNA by one codon |
|
|
Explain Termination (translation)
|
Happens when a stop codon (UAA, UAG, and UGA) is recognized by a release factor in the A site.
1. Release factor bings to stop codon at the A site. 2. Bond between polypeptide and tRNA hydrolyzed to release polypeptide from the P site. 3. Ribosomal subunits and release factors disassociate. |
|
|
What is operon regulation?
|
Genes for related enzymes are grouped together with a single promoter, produces 1 mRNA for all the polypeptides
|
|
|
What is epigenetic regulation?
|
A way to regulate gene expression
Hereditable changes not due to changes in DNA sequences but in addition to the DNA sequences. heavy menthylated areas inactive genes. |
|
|
What human diseases are related to genomic imprinting?
|
Prader Willis and Angelman's
|
