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109 Cards in this Set
- Front
- Back
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What are the major components of DNA? |
4 bases deoxyribose backbone |
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What are the major components of RNA? |
4 bases (uracil!) ribose backbone |
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direction nucleic acids are synthesized... |
5' to 3' direction |
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DNA polymerase requires |
1. a template 2. a set of dNTPs 3. a primer |
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replication of chromosomal DNA begins at |
origin of replication |
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the point where helix is unwound and replicated |
replication fork |
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helicase function |
breaks H bonds between nucleotide bases |
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single strand binding proteins function |
prevent strand re-binding |
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topoisomerases function |
control DNA supercoiling |
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DNA primase function |
generates short pieces of RNA to start DNA synthesis |
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DNA polymerase... |
elongates RNA primers |
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DNA ligase function |
joins up adjacent okazaki fragments on lagging strand |
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Link between genes and proteins |
1. genes control biochemical rxns 2. enzymes are proteins 3. genes determine specific primary sequences of amino acids 4. linear sequence in gene determines linear sequence in protein. |
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auxotrophic mutants |
incapable of synthesizing vital cell components without addition of organic nutrients. |
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what determines the phenotype of an organism? |
enzymes polypeptides |
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colinearity |
linear sequence of nucleotides in a gene determines linear sequence of amino acids in a protein |
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promoters |
different promoters are recognized by different RNA polymerases |
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terminators |
when RNA polymerases encounters transcriptional terminator sequence it will transcribe it to RNA. A stem-loop structure forms |
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operons |
genes with similar function grouped together |
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exons |
functional portions that code for proteins |
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introns |
non-coding intervening sequences. |
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fluctuation testing |
if mutation occurred due to phage then number of would be consistent. if mutation occurred at random then would be great variation. |
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errors in DNA replication involving shifts in bases |
transition and transversion |
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DNA strand slippage leading to |
deletions and duplications |
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induced mutations |
incorporation of base analogs. (alternative bases added) 1. replacement of base 2. alteration of base 3. damage to base so can't pair |
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Ames test |
measures the mutagenic effect of chemicals etc. uses bacterial assay |
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dupurination |
spontaneous mutation, insertion of any base |
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deamination |
spontaneous mutation, yeilds uracil. |
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Telocentric |
centromere at one end |
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acrocentric |
centromere off of the centre |
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metacentric |
centromere in the central position |
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telomeres |
can't see with microscope. at the end of xsomes. seal the xsomes. |
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centromere |
responsible for attachment and movement of xsome on spindle. |
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nucleolar organizers |
sites of ribosomal RNA genes. slight constriction of xsome. |
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chromosome 1 is the ... |
largest. |
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heterochromatin is ______ stained. |
densely |
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euchromatin is_________ stained. |
less densely |
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chromatin = |
DNA + protein complex |
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number of chromosomes relates to... |
number of gametes produced. |
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DNA is packaged with the help of |
histones |
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chromosome packing |
DNA is wrapped around nucleosomes. Nucleosomes make up chromatin fibres. |
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constitutive heterochromatin |
permanent feature of specific xsome location |
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facultative heterochromatin |
not always found at a specific location |
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polytene chromosomes |
giant chromosomes. due to repeated rounds of DNA replication without cell division. |
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tandemly repeated ribosomal RNA genes found at the |
nucleolar organizer. |
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exons |
coding regions |
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introns |
non-coding regions |
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eukaryotic DNA is divided into three groups |
1. single-copy functional genes 2. repetitive DNA 3. spacer DNA (non-coding) |
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repetitive DNA is either... |
a) functional or b) has no known function |
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example of non-coding functional sequence is |
telomeres. stabilize xsome, prevent degradation. (tandem arrays- same DNA repeated over and over) |
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example of coding functional sequence is |
tandem gene families. consist of identical DNA sequences. |
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DNA transposons |
DNA elements that move from one position to another as DNA molecules. via "cut & paste" or "copy & paste" requires transponsase enzyme |
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Transposed sequences |
mobile, abundant, able to insert at many different locations, often cause mutations. |
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locus |
where a gene is located |
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chiasmata |
join homologous xsomes. sites of recombination. |
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two kinds of meiotic recombination |
interchromosomal- genes on dif xsomes intrachromosomal- mediated by chiasma |
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linkage maps show that genes close together will recombine... |
less often. |
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recombination can be seen by comparing |
inputs vs outputs of meiosis |
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number of recombinants can never be greater than |
the parentals. |
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interference |
when crossing over in one xsome region affects crossing over in another region. |
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interference calculations |
coefficient of coincidence = observed n.o double xovers/ expected n.o double xovers Interference = 1 - coefficient coincidence when i = 0 (no interference) when i = 1 (complete interference) |
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when genes are linked, parent types are always the |
most frequent progeny. |
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tetrad |
group of four cells retained as products of single meiosis. |
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types of DNA markers |
mini satellite micro satellite SNPs RFLPs |
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SNPs |
position on genome where people differ in a single nucleotide base |
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RFLPs |
a SNP that alters restriction enzyme recognition site |
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four main types of structural chromosome mutations |
deletions, duplications, inversions, translocations |
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deletions |
loss of xsome segments mostly lethal |
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duplications |
addition of extra copy of xsome region |
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inversions |
two breaks in a xsome and rotation 180* common. |
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pericentric |
include centromere. |
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genetic consequences of mutations |
act as crossover supressors lead to creation of "supergenes" decrease fertility change linkage relationship speciation and evolution! |
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translocations |
two pairs of xsomes break and exchange regions. |
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euploids |
multiple copies of whole xsome sets |
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aneuploids |
multiple copies of one or more individual chromosomes |
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autopolyploids |
type of euploid. multiple copies of the same genome. |
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allopolyploids |
type of euploid. multiple copies of different genomes (derived from different species.) |
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aneuploids are... |
less common and usually a consequence of non-disjunction. |
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polyploidy |
organisms have more than 2 sets of xsomes. correlation between number of copies of xsome and size of organism. |
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example of human anueploidy |
down's syndrome |
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sex determination |
the mechanism by which sex is established |
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sex isn't determined by the sex chromosomes but by... |
the genes present on the sex chromosomes |
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XO |
turners syndrome. are female |
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XXY |
klinefelter syndrome. are male |
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male sex determining gene |
SRY gene. gives transcription factor, binds to DNA, stimulates transcription of genes that promote testes development. |
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dosage compensation |
because females have XX. gene product produced would be double that of males. So one X is switched off |
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inactivated X chromosome |
barr body |
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genes on X chromosome involved in deactivation |
XIST - activate on barr body |
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factor responsible for initiating testis formation is... |
the testis determining factor (TDF) |
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X and Y chromosomes are homologous only in the... |
pseudoautosomal regions |
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SOX-9 |
at low levels in male and female genital ridge, upregulated in males. activates expression of anti-mullerian hormone. |
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regulation of genes |
transcriptional control translation of message into protein control of folding |
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activator binding site binds... |
activator proteins |
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operator binds |
repressor proteins |
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positive regulation |
activator doesn't bind = no transcription |
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negative regulation |
repressor binds = no transcription |
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lac operon is _____ controlled |
negatively |
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cis- acting means |
gene product regulates adjacent transcription units. |
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for lactose metabolites to be expressed |
a) lactose must be present b) glucose must absent |
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more glucose = _________ cAMP |
less |
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simultaneous negative and positive control |
negative= inactive repressor allows expression positive= active factor present |
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eg of dual positive and negative control |
the ara operon |
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similarities of regulation of transcription in eukaryotes |
1. promoter sequences vary 2. use activator/repressor proteins |
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differences of regulation of transcription in eukaryotes |
1. role of chromatin 2. need remove intron DNA before translation 3. regulation of mRNA transport into cytoplasm |
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growth requirements for bacteria |
carbon, nitrogen, phosphorus, sulphur, cations, pH buffer |
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virulent bacteriophage |
multiply and lyse host cell |
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temperate bacteriophage |
multiply and lyse host or.. remain in host without destroying it |
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prokaryotes reproduce via |
binary fisson |
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genetic differences in prokaryotes occur through |
mutations |
