Genetics Intro--8/25 Flashcards
DNA contains the ________; RNA contains ______
2’- Deoxyribose x=H; ribose x=OH
_________ are the monomeric units of nucleic acid DNA and RNA
Nucleotides: nitrogenous base, 5-carbon sugar, phosphate
RNA and DNA contain the purine bases ______ & _____
Adenine (A) and guanine (G)
DNA contains the pyrimidine bases ______ and ______ whereas RNA contains ______ and _____
DNA- cytosine (C) and thymine (T)
RNA- cytosine (C) and uracil (U) –>
DNA and RNA are linear sequences of nucleotides linked by _______ between the…
Phosphodiester bonds= between 3’ sugar of one nucleotide and 5’ sugar of next nucleotide
DNA is double stranded: one strand runs _______ whereas the other is antiparallel and runs _____
5’ to 3’ direction and 3’ to 5’
The two strands of DNA wrap about each other to form a _____ and are held together by ________ between bases in each strand
double helix; hydrogen bonding
Adenine H-bonds to _______
Cytosine H- bonds to _______
A-Thymine
C-Guanine
Transcription of a gene generates a _____
single stranded RNA
Three major types of RNA are:
1) messenger RNA - mRNA
2) ribosomal RNA - rRNA
3) transfer RNA- tRNA
plus various other non-coding RNAs
________is modified at both 5’ and 3’ ends. In between it contains a coding region for the synthesis of a protein
Eukaryotic mRNA
Codons within a coding region…..
Each Codon is….
…dictate the sequence of amino acids in a protein
…three nucleotides long
_________ and _______ are required for protein synthesis
rRNA and tRNA
rRNA is complexed with proteins to form ribonucleoprotein particles called _______, which bind ______ and ______ during translation.
Ribosomes; mRNA and tRNA
The tRNA contains an _____ that binds to a complementary codon on mRNA, ensuring insertion of the correct amino acid into the protein being synthesized
Anticodon
…of DNA is important for containing the DNA in the cell and regulation of gene expression–especially in eukaryotes
Packaging/condensing of DNA
DNA combines with proteins called ______ to form nucleosomes that are further condensed into wound ______
histones; chromatin
Where is the DNA in a prokaryote?
cytoplasm of cell
99% of all DNA is found in the _____ of a cell.
Nucleus, separated from rest of cell by nuclear envelope
- small amount of DNA (0.1%) found in mitochondria
Nucleotides are composed of a _____, a ______, and a _______
Base (adenine, guanine, cytosine, thymine, uracil), Sugar, and a phosphate
***MONOMERIC units of Nucleic Acid
Nucleosides lack _____
phosphates
-Think about ATP (Adenine TRIphosphate…)
DNA chains consist of _____ and _____ sugars linked by a ______ created by a _______bond
bases; deoxyribose sugars (x=H); phosphate backbone; phosphodiester bond
The creation of a phosphodiester bond produces ______ that…..
Pyrophosphate ( PPi delta G= -30 KJ) –> provides energy for reaction (favorable reaction with the release of energy)
- *catalyzed by DNA polymerase
- **DNA extends only in the 5’ to 3’ direction
Adenine-Thymine = \_\_\_\_ H-Bonds Guanine-Cytosine= \_\_\_\_\_ H-Bonds
A-T=2
G-C=3
Stacking between bases –>
Major and Minor Grooves
Major Groove allows for proteins to interact with DNA
In each base pair a purine (_____, _____) on one strand forms hydrogen bonds with a pyrimidine ( _____, _____) on the other strand.
Purine–> adenine, guanine
Pyrimidine—> thymine, cytosine
Two strands of DNA are _______
Complementary
The double Helix of DNA confers……
extra strength
The phosphate backbone lies on the ______ of the helix and contains a ______ charged oxygen giving the helix an overall _______ charge that aids in …..
outside; negatively; negative; aids in the binding of proteins and molecules
**charges affect how compact/loose DNA is
Complementary Strands. Explain.
One strand: 5’ carbon lies above 3’ carbon –> 5’ to 3’ direction
Complementary strand: opposite –> 3’ to 5’ direction
Therefore: two strands are antiparallel
Take a break and go watch the videos on the slides. JUST DO IT.
You better have done it.
DNA has ____ types of conformations: ____, _____, and _____
3 Types: B-DNA, A- DNA, Z-DNA
B-DNA is a ______-handed helix. It is the MOST COMMON type and the presumed if not specified.
Right Handed
A-DNA is a ____-handed helix and is found in _______ (Transcription). It is more compact than B-DNA
Right-Handed; DNA-RNA hybids
Z-DNA is a ____-handed helix and is formed _______
Ex. during….
left-handed; transiently (momentarily, briefly)
….transcription
A _____ is all of an organism’s DNA (nuclear and mitochondrial)
genome
The nuclear genome of a human haploid cell (sperm or egg) contains ____ chromosomes….and a haploid sperm/egg combine to form a ________
23 chromosomes…one of each; diploid zygote
**BOM chicka WA WA
All mitotic progeny of a diploid zygote have a homologous pair of _________ and one pair of ______ for a total of ______Chromosomes in a single diploid cell
22 autosomes; sex chromosomes; 46 chromosomes
Chromosomes can be distinguished by their ______, ______, and _______ (which is what?)
size; staining pattern; FISH color (fluorescents that color chromosomes)
_______ are fundamental units of heredity and are arranged linearly along a chromosome
GENES–> contains DNA sequence encoding structural components,regulatory elements…
Each DNA molecule that forms a linear chromosome must contain a ______, two _______ and a ________
centromere, two telomeres, and a replication of origin (Eukaryotes/linear DNA multiple origins???)
a genetic LOCUS refers to the …..
specific location on a chromosome
Each gene in a diploid cell has a corresponding alternate version of the gene on its _________; these alternate gene versions are called ________, thus there are 2 _____ for each gene (one paternal, one maternal)
homologous chromosome, allele, alleles
Heterozygous–>
Homozygous–>
Hetero–> alleles function differenty Aa
Homo–> alleles function same AA or aa
Complexity of genome corresponds to ….
total genome size—human genome significantly larger than other genomes
***complexity–> how we utilize those genes (mice vs. human)
Exons–>
codes for a portion of a protein
Introns–>
Non-coding, spliced out
Eukaryote Packaging: DNA binds to ______ that contain large amounts of ____and ____because they are _____charged. This complex is called ______
HIstones; arginine & Lysine–> positive charge to bind to negative DNA backbone; histone-DNA complex=Chromatin
*essential for transcription
_____are the basic unit of Chromatin (beads on string)
Nucleosome
Strings of nucleosomes wind into helical, tubular coils called ______
solenoids
Each of the core of histones has a long N-terminal amino acid ____ which….
Tails-> perform critical functions in regulating chromatin structure
*****subject to covalent modifications
Tails are modified by _____of lysines, ______ of lysines, and _____ of serines.
acetylation and methylation of lysine, phosphorylation of serines
Acetyl groups are added to the histone tails by ______and are taken off by ______
ON–>acetyltransferases (HATS
OFF–> de-acetyltransferases (HDACs)
- targeted by drugs (especially cancer)
- **HDAC upregulated in cancer–>silence of p53 tumor suppressor gene
- *****Therefore HDAC inhibitors are anticancer drugs
Histone acetylation plays a crucial role in…..
destabilizing chromatin because acetyl group removes overall + charge from lysine making it more difficult to neutralize negative charge of DNA
**acetylated histones don’t pack well
***Acetyl groups change gene expression
Euchromatin:
Heterochromatin:
E–> loose chromatin ready for transcription/replication
H–> most highly condensed, closed to processes
acetylation of tail histones associated with –>
deacetylation associated with –>
Acetylation–> euchromatin
Deacetylation–> heterochromatin
Genes can be silenced by …. not just by mutation
chromatin condensation so that genes can’t be expressed
Uracil and thymine differ only by a ______ in thymine
methyl group
RNA chains are typically _____ stranded but they can form..
single stranded; secondary and tertiary structures due to base pair with self—>tRNA
mRNA contains a _____ sequence that is converted into the ______ of a polypeptide chain by the process of Translation
nucleotide sequence; amino acid sequence
Processing mRNA involves…
1) adding 5’ guanosine cap
2) …protein coding sequence…
3) poly-A tail
4) splicing out non-coding sequences (introns)
***post processing–> transfer to cytoplasm for translation
Ribosomes contain _____ and are complexes on which ….
rRNA; protein synthesis occurs
Prokaryotic ribosomes have 3 types of rRNA:
5S, 23S, and 16S
Eukaryotic ribosomes have 4 types of rRNA:
5S, 5.8S, 18S, and 28S
tRNA molecules carry amino acids to ribosomes and ensure….
that they are incorporated into correct position in polypeptide chain
There is one tRNA for each _______
amino acid –>20
Oligonucleotides serves as…
primer for DNA rep
small nuclear ribonucleoproteins (snRNPs) are involved in _____
splicing
microRNAs (miRNA) are ____ RNA with key functions in development, cell differentiation, regulation, and cells cycle/apoptosis
non-coding
