Unit 6 Flashcards
Two types of nucleic acids
DNA and RNA
How can nucleic acids store and carry information
nucleic acids are large molecules that carry information in the sequence of nucleotides
Role of DNA
contains information to specify the amino acid sequences of proteins
Role of RNA
Protein synthesis
Regulation of gene expression
RNA sugar
Ribose
-OH (hydroxyl group)
DNA sugar
Deoxyribose
Hydrogen
Adenine and thymine bond with (2/3) hydrogens
2
Cytosine and guanine bond with (2/3) hydrogens
3
What about DNA allows it to code for genetic information of all living organisms?
No restriction on the sequence of bases along a DNA strand
Protein functions (3 examples)
- acts as enzymes that speed up chemical reactions
- acts as channels in the cell membrane
- provides structural support for the cell
Transcription
Synthesis of RNA from a DNA template
Translation
Process in which a protein is synthesized from RNA
Central Dogma
basic flow of information in a cell
DNA –> RNA –> Protein
Segment of DNA that codes for a particular protein
Gene
Gene regulation
various ways in which cells control gene expression
Noncoding RNA’s
DNA is transcribed to RNA, but RNA is not translated to proteins
Central Dogma in Eukaryotic cells
Transcription occurs in nucleus
Translation occurs in cytosol
independent events
Central Dogma in Prokaryotic cells
Transcription and translation occur in the cytoplasm
occur at the same time
Chromosomes in Prokaryotic cells
DNA has supercoils that form nucleoids to package in DNA (rubber band example)
Plasmids
In prokaryotic cells, all circles of DNA that replicate independently of the cells circular chromosome
Chromosomes Eukaryotic cells
Linear chromosomes
DNA loops around histone proteins
Scaffolding proteins act to condense chromosomes
Replication Fork
site where the parental DNA strands separate as the DNA duplex unwinds
Helicase
separates the strands of the parental double helix by breaking the hydrogen bonds between the base pairs
DNA polymerase
makes copies of DNA
Topoisomerase
relieves stress from the unwinding the double helix
Two properties of DNA polymerase
- can only attach a nucleotide to an existing nucleotide
- can only add nucleotides to the 3’ end (not the 5’ end)
Primers
short RNA strands that act as a starter for new DNA strands
Enzyme that synthesizes the RNA primer
RNA primase
Chemical bases for adding a nucleotide to DNA
DNA polymerase adds nucleotides to the 3’ end, the hydroxyl group breaks one of the nucleotide’s phosphates providing energy while the outmost phosphates are released.
Leading strand
daughter strand with 3’ end toward the replication fork
Lagging Strand
daughter strand with 5’ end towards the replication fork
RNA primase
lays down an RNA primer
DNA polymerase
extends the RNA primer
Second DNA polymerase
removers the primer and replaces it with DNA
DNA ligase
an enzyme that joins DNA fragments together
Process of DNA replication (4 points)
- RNA primase lays down an RNA primer
- DNA polymerase extends the RNA primer
- Different DNA polymerase removes he primer and replaces it with DNA
- DNA ligase joins the 2 DNA fragments
Proofreading
process in which a DNA polymerase can immediately correct its own errors
positive regulation
activator binds to DNA site and causes transcription
negative regulation
repressor binds to DNA site and inhibits transcription
Inducer
binds to repressor to stop it from binding with DNA
