micro midterm Flashcards
single molecules(monomers) that make up proteins(polymers) called?
AMINO ACIDS
R group present on glycine?
Hydrogen(H) grp
R group present on Alaine?
Methyl(CH3)
R group present on Cysteine
Sulfhydryl(CH2SH)
Covalent bond btw two amino acids?
peptide bond
Two amino acids joined by a peptide bond through a process of dehydration synthesis is?
Dipeptide
4-9 amino acids joined by peptide bonds
peptide
10-2,000 or more amino acids joined by peptide bonds are?
polypeptides(proteins)
primary structure
the number and sequence of amino acids(AA’s) in a single polypeptide chain
secondary structure
H-bond interactions btw AAs of a single polypeptide chain forms a coiled structure: an a-helix or b pleated sheet
tertiary structure
the helix of a single polypeptide chain folds irregularly on itself due to R group interactions btw AA forming DISULFIDE bonds or other bonds. a supercoiled structure formed
- 2 degree and 3 degree structure determine proteins 3D shape and function
Quaternary Structure
2 or more polypeptide chains are joined together, usually by disulfide bonds
disulfide bonds
bond formed when two cyteines( types of amino acids) are joined
proteins attached to organic compound are called?
conjugated proteins
ex: glycoprotein. lipoprotein, nucleoprotein, hemoglobin
which organic compounds are classified as nucleic acids?
DNA and RNA
what are the building blocks(monomers) of nucleic acids called?
nucleotides
3 components that make up each nucleotide?
- pentose sugar
- phosphate group
- nitrogen base(A,G,T, or C)
which component distinguishes the 4 types of nucleotides from each other?
nitrogen base(N-base)
which N bases are purines?
Adenine(A)
Guanine(G)
which N bases are Pyrimidines?
Cystosine(C)
Thymine(T)
or Uracil(U) in RNA
who discovered the structure of the DNA molecule?
James watson & francis crick
James and Crick findings?
1) two chains of nucleotides joined at nitrogen bases by H-bonds
2)Complementary base pairing between nitrogen bases
A w/ T(2h bonds)
C w/ G(3h bonds)
3) two chains of nucleotides(base pairs) from a double helix(twisted ladder configration)
- sugar-phosphate backbone forms sides of ladder
- nitrogen bases from rungs of ladder
4) the two chains are oppositely orientated, anti parallel
- 1st nucleotide chain begins at C #5 and ends at C #3 on deoxyribose.
- 2nd nucleotide chain begins at C #3 and ends at C #5 on deoxyribose)
DNA
5’ AAA TTT CCC CAC 3’
3’ TTT AAA GGG GTG 5’
DNA
- double stranded
- nitrogen base: A<G
- A bonds with T
- C bonds with G
- deoxyribose sugar is missing oxygen on carbon 2
- longer molecule containing thousands of genes
RNA
-single stranded
-nitrogen bases: A<u><G
-A bonds w/ U
C bonds w/ G
-ribose sugar has oxygen on carbon number 2
-shorter molecule decoded from one gene</u>
genetics
the study of the structure, function, and transfer of genes from one generation to the nexy
chromosome
structure containing the hereditary information(genes) of the cell
gene
segment of DNA that codes for(give instructions or recipe for) trait/characteristics/protein/phenotype in an organism
genotype
genetic make up of an individual, eukaryotes have paired genes;
prokaryote have single genes
phenotype
- trait or protein
- physical or physiological expression of a gene resulting from a genotype
Genome
sum of all genes in cells of organisms
- include plasmids if present
- e coli=5,000-10,000
DNA replication
- duplication of chromosomes prior to cell division
- identical genes passed to next generation(daughter cells)
protein synthesis
- gene expression at the ribosome
- making of proteins from copied genes
- 2 process
- transcription: a gene in a DNA is copied into an mRNA transcript, a copied gene
-recombination: a piece of DNA containing several genes is passed from donor to recipient bacterial cells in same generation
3 steps in DNA replication
1) unzipping: helicase unwinds DNA and breaks hydrogen bonds holding the two chains together, exposing nitrogen bases on each template strand of DNA
2) complementary copying of each template strand inDNA:
DNA polymerase complementary base pairs free DNA nucleotides in the cytoplasm with each nitrogen base on each template strand in a 5’ to 3’ direction
3) Termination of replication: the two new molecules of DNA rewind and separate
which enzyme proofreads for errors during DNA replication?
DNA polymerase
what would happen if the enzyme that proofreads for error during replication misses the error?
MUTATION
define SEMIconservative replication
-produces 2 new molecules of DNA each with one original strand and one newly synth strand
what direction is the template stand on DNA copied?
5 to 3
protein synthesis
gene expression at the ribosome making protein from copied gene
components invovled in protein synthesis
1) DNA gene: segment of DNA that codes for a trait/protein/phenotype/characteristic of an organism
2) 3 types of RNA
- mRNA: carries copied gene(RNA transcript) to ribosome during translation.
- rRNA: Unkown
- tRNA: carries amino acids to ribosomes during translation
3) genetic code: rules that determine how a nucleotide sequence in a gene encodes an amino acids sequence in a protein.
why is the genetic code called a degenerate(redundant code)
more than one mRNA codon can encode the same AA
mRNA codons encode for?
AMINO ACIDS
nonsense mRNA codons(UGA,UAG,UAA)
do not code for amino acids
start mRNA codon
AUG founds at the beginning of mRNA transcript and codes for the AA methionine
-it initiates translation of AA in protein
stop/terminator mRNA codons
- UGA, UAG, UAA(nonsense codon)
- always found at the end of an mRNA transcript and terminates translation
Transcription
-a gene in DNA is copied into a mRNA transcript, a copied gene
3 steps:
A) initiation: RNA polymerase binds promoter sequence prior to DNA gene, it complementary copies 1st triplet nucleotide–> AUG
B) Elongation: RNA polymerase moves along the template strand in DNA gene and complementary base pairs free RNA nucleotides w/ each DNA nucleotide in a 5’ to 3’ direction, producing an mRNA transcript.
C) termination: mRNA transcript encodes a specific sequence of amino acids in a protein at the ribosome
introns
non-coding portion of DNA that do not code for AA in proteins
exons
coding portions of DNA that code for AA in protein, are transcribed by RNA polymerase into a pre-mRNA transcript
splicing
ribozymes in nucleus remove(cut out) intron-deived RNA and splice together exon-derived RNA into a mature mRNA, which is further modified and passes thru pores of the nuclear membrane into the cytoplasm, where it directs protein synthesis at the ribosome
mutation
- alteration of gene
- change in base sequence of DNA in a gene
frequency of mutation
-the probability that a gene will mutate when the cel divides or replicate
spontaneous mutation
arise as a result of errors in replication at a rate of 1 in 10(9) replicated base pairs or 1 in 10(6) replicate genes
induced mutation
mutagenic agents(mutagens) in the environment that increase the mutation rate to 1 in 10(5)(1/100,000) or 1 in 10(3) (1/1000) replicated genes during DNA replication. -mutagenic agents damage DNA and interfere with its functioning