Chapter 7 Flashcards
What is a Genome?
Complete set of genetic information
Human: 46 chromosomes
Bacteria: extra chromosomal DNA & nucleoid
What is a gene?
Specific selection of nucleotides that codes for a polypeptide
What is DNA replication?
Copies genetic material to create new DNA strands
3 main characteristics of DNA Replication:
- Bidirectional (creates 2 replication forks that meet at terminating site)
- Semiconservative- new DNA contains one original & one new strand
- Origin of Replication- where it begins
What is Gene Expression?
Making proteins through the processes of transcription & translation.
Nucleotide strands are ______ & _______?
Complementary & antiparallel
Role of mRNA:
-“messenger”
Acts as a chemical “blueprint” for a protein product
Role of tRNA:
- “transfer”
- recognizes specific codon & transfers the corresponding amino acid to the growing polypeptide chain.
- contains the ANTICODON
Role of rRNA:
- “ribosomal”
- central unit of ribosome
- provides mechanism for decoding mRNA into amino acids
What controls the level/speed of protein synthesis?
Cells
-rapid degeneration of mRNA leads to generation of more proteins
What is a Replisome?
- enzymes & proteins that synthesize DNA
- “assembly line”
What is DNA gyrase?
An enzyme that temporarily breaks the strands of DNA, relieving tension from unwinding strands.
What is DNA ligase?
An enzyme that joins two DNA fragments by forming a covalent bond between the sugar/phosphate of adjacent nucleotides.
DNA Polymerase:
Enzymes that synthesizes DNA by using one strand as a template to make a complimentary strand by adding nucleotides to the 3’ end.
In what direction does DNA Polymerase synthesize in?
3’ to 5’
RNA Polymerase:
Enzymes that synthesize RNA strands based on the DNA template by assembling individual nucleotides
What direction does RNA Polymerase synthesize?
5’ to 3’
What is the difference between 5’ and 3’?
Five prime- has a phosphate group attached to itself
Three prime- has a hydroxyl group attached to itself
What is a helicase?
Enzyme that unwinds the DNA helix ahead of the replication fork
What is a Primer?
Fragment of nucleic acid to which DNA polymerase can add nucleotides
What is an Operon?
A bacterial transcript (RNA) that contains information for more than one gene.
True or False: DNA Polymerase and RNA Polymerase both require a primer.
False. Only DNA Polymerase requires a primer to synthesize DNA
DNA template is the ______ strand?
(-) minus strand
Compliment is _____ strand?
(+) positive strand.
RNA has the same nucleotide sequence as the _______ DNA strand.
Positive (+).
DNA(+) : 5’ GCTGATGAT 3’
DNA (-) : 3’ CGACTACTA 5’
RNA : 5’ GCUGAUGAU 3’
What is a Promotor?
Nucleotide sequence to which RNA Polymerase bonds to initiate transcription
What is the Sigma Factor?
Component of RNA Polymerase that recognizes the promoter region.
What is a terminator?
Nucleotide sequence at which RNA synthase stops & RNA Polymerase falls off the template
What is a Codon?
Three nucleotides held together by hydrogen bonds.
Why is a genetic code redundant or degenerate?
Because a single amino acid may be coded for more than one codon.
Ex. AUU & AUC both point to Isoleucine
How many reading frames are there for codons?
3
Depend on start of coding region
What is the purpose of a ribosome?
-to synthesize proteins
Where does protein synthesis occur in prokaryotic cells?
Within the cutoplasm
Where does protein synthesis take place in eukaryotic cells?
RNA is produced in the cell’s nucleus, and then moved to the cytoplasm to preform protein synthesis.
