-
DNA has the capacity to:
and can be:
- store genetic information
- copied and passed from generation to generation
-
DNA and RNA are ____ _____
nucleic acids
-
chemical units that DNA and RNA are consisted of
nucleotides
-
joins nucleotides
sugar-phosphate backbone
-
DNA backbone consists of:
deoxyribose sugars and phosphate groups (sugar-posphate backbone)
-
The four nucleotides found in DNA differ in their nitrogenous bases:
RNA has _ instead of _
T, C, A, and G; U instead of T
-
The model of DNA is like a rope ladder twisted into a spiral
-The ropes at the sides represent the _______
-Each wooden rung represents _______
- -sugar-phosphate backbones
- -a pair of bases connected to hydrogen bonds
-
DNA bases pair in a complementary fashion:
Why?
- -A with T
- -C with G
- -Because of the number of hydrogen bonds they want to make
-
When a cell reproduces, a complete copy of the DNA must _____
Watson and Crick's model for DNA suggested that _______
- -pass from one generation to the next
- -DNA replicates by a template (patterned) mechanism
-
DNA can be damaged by ____
ultraviolet light
-
enzymes that make the covalent bonds between the nucleotides of a new DNA strand; they are involved in repairing damaged DNA
DNA polymerases
-
DNA replication in eukaryotes:
-Begins at specific sites on a ____ ____
-Proceeds __________
- -double helix
- -in both directions
-
DNA functions as the ________
inherited directions for a cell or organism
-
An organism's genetic makeup; the sequence of nucleotide bases in DNA
genotype
-
the organism's physical traits, which arise from the actions of a wide variety of proteins
phenotype
-
DNA specifies the synthesis of proteins into two stages: ___ and ___
transcription and translation
-
the transfer of genetic information from DNA into an RNA molecule
transcription
-
the transfer of information from RNA into a protein
translation
-
-The function of a gene is to ____
-A protein may consist of two or more different ___
- -dictate the production of a polypeptide
- -polypeptides
-
Genetic information in DNA is:
1.
2.
- 1. transcribed into RNA, then
- 2. translated into polypeptides
-
What is the language of nucleic acids?
- -in DNA, it is the linear sequence of nucleotide bases
- -a typical gene consists of thousands of nucleotides
- -a single DNA molecule may contain thousands of genes
-
When DNA is transcribed, the result is ____
an RNA molecule
-
RNA is then translated into _____
a sequence of amino acids in a polypeptide
-
a triplet of bases which codes for one amino acid
codon
-
the set of rules relating nucleotide sequence to amino acid sequence; shared by all organisms
genetic code
-
of the 64 triplets:
- -61 code for amino acids
- -3 are stop codons, indicating the end of a polypeptide
-
Transcription
- -DNA to RNA
- -makes RNA from a DNA template
-
links RNA nucleotides
RNA polymerase
-
RNA substitutes a _ for a _
U for a T
-
Initiation of Transcription
- -first phase of transcription
- -RNA polymerase attaches to the promoter
- -RNA synthesis begins
-
a nucleotide sequence with the "start transcribing" signal
promoter
-
RNA elongation
- -second phase of transcription
- -RNA grows longer
- -RNA strand peels away from the DNA template
-
Termination of Transcription
- -third phase of transcription
- -RNA polymerase reaches terminator
- -polymerase detaches from the RNA
- -the DNA strands rejoin
-
After transcription, before translation
- -eukaryotic cells process RNA
- -prokaryotic cells do not
-
RNA processing
- -adding a cap and tail
- -removing introns
- -splicing exons together to form messenger RNA
-
the conversion from the nucleic acid language to the protein language
translation
-
Translation requires:
- -mRNA
- -ATP
- -enzymes
- -ribosomes
- -transfer RNA
-
Transfer RNA (tRNA)
- -acts as a molecular interpreter
- -carries amino acids
- -matches amino acids with codons in mRNA using anticodons
-
Ribosomes:
- -coordinate the functions of mRNA and tRNA
- -are made of two protein subunits
- -make proteins
- -contain ribosomal RNA (rRNA)
-
Initiation during Translation:
- brings together:
- -mRNA
- -the first amino acid, Met, with its attached tRNA
- -two subunits of the ribosome
-
the mRNA molecule has a ___ and a ____ that help it bind to the ribosome
cap and a tail
-
Initiation of Translation occurs in two steps:
- -first, mRNA molecule binds to a small ribosomal unit, then an initiator tRNA binds to the start codon
- -second, a large ribosomal subunit binds, creating a functional ribosome
-
Elongation of Translation occurs in ____ steps:
three steps
-
the anticodon of an incoming tRNA pairs with the mRNA codon at the A site of the ribosome
codon recognition; first step in elongation during translation
-
the polypeptide leaves the tRNA in the P site and attaches to the amino acid on the tRNA in the A site; the ribosome catalyzes or activates the bond formation between the two amino acids
peptide bond formation; second step in elongation during translation
-
the P site tRNA leaves the ribosome; the tRNA carrying the polypeptide moves from the A to the P site
translocation; third step in elongation during translation
-
Termination: elongation continues until:
- -the ribosome reaches a stop codon
- -the completed polypeptide is freed
- -the ribosome splits into its subunits
-
in a cell, genetic information flows from DNA to RNA in the ______ and RNA to protein in the ______
nucleus; cytoplasm
-
any change in the nucleotide sequence of DNA
mutation
-
the replacement of one base by another
base substitution
-
the loss of a nucleotide
nucleotide deletion
-
the addition of a nucleotide
nucleotide insertion
-
insertions and deletions can:
-change the reading frame of the genetic message
-
physical or chemical agents that may cause mutations
mutagens
-
Viruses are not living organisms because they:
-are not cellular and cannot reproduce on their own
-
viruses that attack bacteria
bacteriophages
-
the first reproductive cycle of phages; many copies of the phage are made within the bacterial cell and then the bacterium lyses or breaks down
lytic cycle
-
the second reproductive cycle of phages; the phage DNA inserts into the bacterial chromosome and the bacterium reproduces normally, copying the phage at each cell division
lysogenic cycle
-
an enzyme used by retroviruses to synthesize DNA on an RNA template
reverse transcriptase
-
misfolded proteins that somehow convert normal proteins to the misfolded prion version; give an example
prions; mad cow disease
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