BIO 160 Chapter 10 Flashcards
Chemical compositions DNA vs RNA
DNA RNA
Stands for: DeoxyriboNucleicAcid RiboNucleicAcid
Definition: A nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. RNA, single-stranded chain of alternating phosphate and ribose units with the bases adenine, guanine, cytosine, and uracil bonded to the ribose. RNA molecules are involved in protein synthesis and sometimes in the transmission of genetic information.
Job/Role: Medium of long-term storage and transmission of genetic information The main job of RNA is to transfer the genetic code need for the creation of proteins from the nucleus to the ribosome. this process prevents the DNA from having to leave the nucleus, so it stays safe. Without RNA, proteins could never be made.
Unique Features: The helix geometry of DNA is of B-Form. DNA is completely protected by the body i.e. the body destroys enzymes that cleave DNA. DNA can be damaged by exposure to Ultra-violet rays The helix geometry of RNA is of A-Form. RNA strands are continually made, broken down and reused. RNA is more resistant to damage by Ultra-violet rays.
Predominant Structure: Typically a double- stranded molecule with a long chain of nucleotides A single-stranded molecule in most of its biological roles and has a shorter chain of nucleotides
Bases & Sugars: DNA is a long polymer with a deoxyribose and phosphate backbone and four different bases: adenine, guanine, cytosine and thymine RNA is a polymer with a ribose and phosphate backbone and four different bases: adenine, guanine, cytosine, and uracil
Pairing of Bases: A-T(Adenine-Thymine), G-C(Guanine-Cytosine) A-U(Adenine-Uracil), G-C(Guanine-Cytosine)
Stability: Deoxyribose sugar in DNA is less reactive because of C-H bonds. Stable in alkaline conditions. DNA has smaller grooves where the damaging enzyme can attach which makes it harder for the enzyme to attack DNA. Ribose sugar is more reactive because of C-OH (hydroxyl) bonds. Not stable in alkaline conditions. RNA on the other hand has larger grooves which makes it easier to be attacked by enzymes.
Describe the key features of the overall shape of a DNA molecule
double helix, sugar phosphate backbone.. base pairs inside..
Explain how the structure of DNA was determined
Crick was studying protein structure using x-ray crystallography. saw a x-ray image, saw basic shape was a helix the thickness of helix suggested two polynucleotides.. put backbones on the outside
What is the polarity of DNA?
negative
molecular bology
study of heredity at the molecular level
nucleotides
long chains of chemical units
full name of DNA
deoxyribonucleic acid
deoxyribose
sugar missing an oxygen
single ring structures
Cytosine and Thymine
double ring structures
Adenine and Guanine
Uracil
replaces Thymine in RNA
ribose
sugar in RNA
polynucleotide strands
double helix
DNA polymerases
enzymes that make the covalent bonds between the nucleotides of a new DNA strand
molecular chain of command
DNA=>RNA=> protein synthesis
transcription
transfer of genetic information from DNA to RNA
translation
translation from RNA to protein
why is one gene one enzyme not correct?
keratin is a product of a gene, many proteins have two or more different polypeptide chains.. each plypeptide is specified by its own gene
codons
three-base words
genetic code
the set of rule that convert a nucleotide sequence in RNA to an amino acid sequence
AUG
start of a polypeptide chain and Methionine
stop codons
UAA UGA UAG
promoter
start transcribing signal
RNA Elongation
2nd phase of transcription, RNA grows longer
terminatior
end of the gene, 3rd phase of transcription
mRNA
messenger RNA, the molecule that is translated into protein
cap and tail
protect the RNA from attace by cellular enzymes and help ribosomes recognize the RNA as mRNA
introns
noncoding regions
exons
the coding regions - theparts of a gene that are expressed
RNA splicing
introns are removed and exons are joined
Translation players
mRNA, tRNA and Ribosomes
tRNA
transfer RNA, the molecular interpreter.. pick up appropriate amino acids, and recognize the appropriate codons
anticodon
on tRNA like the codon triplet on mRNA
ribosomes
organelles that coordinate the functioning fo fthe mRNA and tRNA and actually make polypeptides
Translation Process
initiation, Elongation, Termination
Initiation
mRNA molecuel binds to a small ribosomal subunit.. tRNA binds to the start codon the initiator tRNA carries the amino acid methionine, anticodon A large ribosomal subunit binds to the small one, creating a functional ribosome
Elongation
amino acids are added one by one to the first amino acid,
1. Codon Recognition
2. Peptide bond formation
3 Translocation
mutation
any change in the nucleotide sequence of DNA
virus
genes in a box
bacteriophages
viruses that attack bacteria, bacteria eaters
lytic cycle
after many copies of the phages are produced within the bacterial cell, the bacteria breaks open
lysogenic cycle
viral DNA replication occurs without phage production or the death of the cell, many cell divisions.. prophage
HIV
RNA virus with special twists
retrovirus
RNA virus that reproduces by means of a DNA molecule
reverse transcriptase
catalyzes reverse transcripton:Synthesis of DNA on an RNA template
provirus
Viral DNA inserted into Chromosomal DNA
viroids
small circular RNA molecules that infect plants
prions
infectious protiens that cause brain diseases in animals
