Chapter 7.1-7.2 Flashcards
What does RNA stand for
Ribonucleic acid
What does DNA stand for
Deoxyribonucleic acid
Types of RNA
Messenger
Ribosomal
Transfer
tRNA
Transfer RNA
Brings amino acids to ribosomes where they are joined together to form proteins
rRNA
Ribosomal RNA
Helps form ribosomes, where the proteins are assembled
Anticodon
mRNA
Messenger RNA
Copies the genetic instructions from DNA in the nucleus, and carries them to the cytoplasm
DNA
Contains genes, instructions for all of the proteins that your body makes
Found in chromosomes
Central dogma of molecular biology
DNA > RNA > protein
RNA
Carries information of DNA to ribosome and helps assemble the proteins
Chargaff’s rules
Concentrations of four bases differ in different species, yet adenine = thymine and guanine = cytosine
What are the four bases
Adenine
Thymine
Guanine
Cytosine
Structure of DNA
Double helix
Two polynucleotide chains
Who are given credit for discovering structure of DNA
Watson and Crick
What does the polynucleotide chain consist of
A sugar
A phosphate group
A nitrogen containing base (a,t,g,c)
How are the two polynucleotide chains held together in DNA
Hydrogen bonds
Bonds between A-T, and G-C
DNA replication
Process in which DNA is copied
Occurs during S (synthesis) phase
Enzyme breaks bonds between two polynucleotide chains of parent molecule
Other enzyme pairs new, complementary nucleotide with those in the two parental chains
Two daughter DNA molecules form, each containing one new chain
RNA vs. DNA
RNA- smaller, one nucleotide chain, contains uracil (U) instead of thymine, contains sugar ribose instead of deoxyribose
Where are proteins made
On the ribosomes in the cytoplasm
Who first concluded that DNA is the genetic material in cells
Oswald Avery
Who confirmed that DNA is the genetic material
Hershey and Chase
Protein synthesis
The process in which cells make proteins
Transcription-nucleus
Translation-ribosome
Transcription
DNA > RNA
Initiation
Elongation
Termination
Initiation (Transciption step 1)
Enzyme polymerase binds to region of gene called promoter
This signals DNA to unwind so the enzyme can read the bases in one of the DNA strands
The enzyme is ready to make a strand of mRNA with a complementary sequence of bases
Elongation (Transcription step 2)
Addition of nucleotides to the mRNA strand
Termination (Transcription step 3)
mRNA strand is complete and it detaches from the DNA
Triplet
Group of three successive nucleotide bases in DNA
Codon
Group of three nucleotide bases in mRNA that corresponds with the triplet
Why process mRNA more before it leaves the nucleus in eukaryotes?
It allows a single gene to be used to make more than one protein
Splicing
Removes introns from mRNA
Introns are regions that don’t code for proteins
Then it consists of only exrons, which are regions that do code for proteins
Editing
Changes some of the nucleotides in mRNA
Polyadenylation
Adds a "tail" to the mRNA Tail consists of string of adenine bases Signals end if mRNA Involved in exporting mRNA from nucleus Protects mRNA from enzymes that might make it break down
Genetic Code
Consists of bases A,T,G,C
Letters grouped to form codons
Each codon stands for one amino acid/stop/start
20 common amino acids, 64 possible codons
Stop codons
UAG
UGA
UAA
Start codon
Aug- methionine
Characteristics of genetic code
Universal-all living things have same genetic code
Unambiguous-each codon codes for just one amino acid/start/stop
Redundant-most amino acids are coded by more than one codon
Translation
RNA > Protein
mRNA moves to ribosomes high reads sequence, tRNA brings corresponding amino acids
Bonds form between amino acids, forming polypeptide chain, which keeps growing until a stop codon is reached
May assume folded shape, bond with other polypeptides or molecules, and many go to Golgi apparatus to be modified for specific job they will do
