Exam 3 Ch. 11 Flashcards
Structural Elements of DNA
Nitrogenous base
5 carbon sugar
Phosphate group
Double helix
What are the nitrogenous bases of DNA
Adenine
Thymine
Guanine
Cytosine
Structural Elements of RNA
Nitrogenous base
Ribose
Phosphate group
Single stranded
Nitrogenous bases of RNA
Adenine
Uricil
Guanine
Cytosine
Semi Conservative DNA Replication
Parent strand is unwound and separated (Helicase)
New strands form through complimentary base pairing (DNA Polymerase)
DNA Ligase seals any breaks in sugar-phosphate backbone
New DNA will be half an old strand, half a new strand
Enzymes involved in DNA Replication
Helicase
DNA Polymerase
DNA Ligase
Helicase
Unwinding enzyme
DNA Polymerase
Binding enzyme
DNA Ligase
Stitches breaks in DNA after replication
Semiconservative means
Each new DNA molecule is made of one parent template strand and one new strand
3 Types of RNA
mRNA (Messanger)
tRNA (Transfer)
rRNA (Ribosomal)
mRNA
carries genetic information to ribosomes
tRNA
transfers amino acids to ribosomes
(Each tRNA can only carry one type of amino acids)
rRNA
joins with proteins to form ribosome subunits
Transcription
Complimentary mRNA is made from a DNA template
Portion of DNA unwinds and unzips at the point of attachment of RNA polymerase
Bases join in the order dictated by the sequence of bases in the template (using U instead of T)
DNA is copied into mRNA
What strand of DNA is used in transcription
Template
Enzyme involved in Transcription
RNA Polymerase
mRNA Processing
Addition of Poly-A tail and cap
Introns removed
Alternative splicing can produce different versions of mRNA leading to different proteins
Mature mRNA leaves nucleus and binds with ribosome in cytoplasm
Translation
tRNA brings in amino acids
Each codon codes for a specific amino acid to form a polypeptide chain
After translation a protein contains the sequence of amino acids originally specified in DNA
Process by which a protein is synthesized from the information contained in a molecule of mRNA
Enzyme used in Translation
Ribosomes
Splicing
Introns are removed and exons are joined together which can produce different versions of mRNA leading to different proteins
Where does splicing occur
In the nucleus immediately after transcription
What is an Operon
A cluster of bacterial genes that can be selectively expressed and repressed
Where is an operon located
Bacteria
Transcription factors
DNA binding proteins that help RNA polymerase bind to a promoter
Similarities between DNA and RNA
Both nucleic acids
Composed of nucleotides
Sugar-phosphate backbone
4 different bases
Differences in DNA and RNA
DNA: Double Stranded A T C G Genetic Material Deoxyribose
RNA:
Single stranded
A U C G
Ribose
Promoter
Where RNA Polymerase binds prior to transcription
RNA Polymerase
binds nucleotides in trasncription
Does transcription or translation come first?
Transcription done by mRNA
Primary RNA
Before mRNA undergoes processing
Mature RNA
After mRNA undergoes processing
Introns
Segments of DNA that do not code for proteins
Splicing
Removing introns and binding exons
3 phases of translation
Initiation
Elongation
Termination
Initiation
Brings all translation components together
Elongation
Polypeptide chain increases in length one amino acid at a time
Termination
When stop codon appears
Which direction are new nucleotides added
5–3
What are transcription factors
DNA binding proteins that help RNA polymerase bind to a promoter
