Science Exam Poo Flashcards
What makes up a nucleotide
A nitrogenous base, a sugar (ribose or deixyribose), and a phosphate group
What is chargoffs rule
The total number of purines (A and G) is equal to the total number of pyrimidines
What did meischer do
First person to observe DNA, broke down nuclei of wbc and found grey substance called nuclein
What did Levene do
Discovered what nucleotides are made of and made DNA model formed of polynucleotide chains
What did chargoff do
Discovered that there is the same number of purines as pyrimidines
What did Franklin do
Produced first image of DNA using x-ray crystallography to show DNAs diffraction pattern
What did Watson and crick do
Researching DNAs 3D shape, stole Franklin’s image and published a paper about the double helix, awarded Nobel prize
What enzymes are involved in DNA replication
Helicase, primase, DNA polymerase III, DNA polymerase I, ligase
Helicase
Unzips DNA
Primase
Lays down primer so DNA polymerase III can build nucleotides
DNA polymerase III
Adds nucleotides to create new DNA strand
DNA polymerase I
Replaces RNA primers with nucleotides
Ligase
Repairs breaks in sugar-phosphate backbone
Okazaki fragments
DNA fragments that are not fully attached to the strand
Transcription
Happens in nucleus, Helicase unzips DNA, RNA polymerase attaches to a promoter and adds complementary mRNA nucleotides, mRNA leaves through nuclear pore
Translation
Happens in cytoplasm, mRNA attaches to ribosome, ribosome lines up complementary tRNA molecules (tRNA anticodons must match mRNA codons), amino acids form peptide bonds and build a polypeptide strand, tRNA detach from amino acids and leave to pick up more
What is the start codon and what does it do
AUG, Signals when to begin translation
What are the stop codons and what do they do
UGA, UAA, and UAG, Signal when to stop translation
Antiparrallel
The DNA strands run in opposite directions parallel to each other
What are the types of chromosomal mutations
Duplication, deletion, inversion, translocation
Duplication (C)
Extra copy of genes are added to chromosome
Deletion (C)
A piece id the chromosome breaks off and is lost
Inversion (C)
A Segment of the chromosome gets reversed
Translocation (C)
A piece of one chromosome breaks off and attaches to another
What is a frame shift mutation
Shifts the “reading frame” of mRNA codons forwards or backwards changing the amino acid sequence (insertion/deletion)
What is substitution/point mutation
When one nucleotides base is substituted for another
What is insertion
When one or more bases are inserted into the DNA making the strand longer
What is deletion
When one or more bases are deleted from the DNA making the strand shorter
Difference between frame shift mutations and point mutations
Frameshift: adds or subtracts bases, effects everything after the mutation point
Point: changes one base, only effects where base is changed
Silent mutation
Has no effect on amino acid coded for since many amino acids are coded for by many codons
Missense mutation
Causes codon to code for different amino acid than original
Nonsense mutation
Causes a stop codon that terminates translation early and often results in nonfunctional protein
How can mutation produce variation in a population and what does that mean
Mutations can give people different traits, looks, etc, mutations/alleles make everyone unique
What is one positive example of a mutation
HbAS, a mutation that causes both normal and sickled cells, provides resistance to malaria
What is one negative example of a mutation
HbSS mutation causes sickled RBCs, resulting in sickle cell disease
Leading strand vs lagging strand
Leading: built continuously, 5’ to 3’
Lagging: built in Okazaki fragments, 3’ to 5’
What is something that causes a mutation called
Mutagen
Where is DNA found in eukaryotes
The nucleus
When does DNA replication occur
Interphase
Almost all errors that are detected are fixed by
DNA polymerase
What organelle helps form proteins
Ribosome
What are the types of RNA
Transfer, Messenger, ribosomal
tRNA
Brings amino acids to ribosome
rRNA
Makes up ribosome, helps bind amino acids
What is another name for a polypeptide
Protein
What part of a DNA molecule Ike is referred to as the code
Nucleotides
Insertion/deletion changes…
The protein produces by the gene
What binds are formed between base pairs
Hydrogen
