Unit 4 Flashcards
The two stages of protein synthesis in order
transcription and translation
DNA to mRNA
Transcription
mRNA to protein
Translation
Steps of Transcription
- DNA unzips (with RNA polymerase) so it can be used as a template to make mRNA
- RNA polymerase adds nucleotides (using complementary base pairing) to the mRNA
- mRNA breaks off and the DNA zips back together, mRNA leaves the nucleus to look for a ribosome
Steps of Translation
1.The ribosome reads mRNA and finds the start codon (AUG).
- A tRNA molecule with a complementary anticodon drops off an amino acid.
- This continues at each mRNA codon, with the tRNA complimentary base pairing and dropping of its amino acid. The amino acids bond together making a polypeptide chain or protein.
- This process repeats over and over until the ribosome reaches a STOP codon.
three-nucleotide sequence on messenger RNA that codes for a single amino acid
codon
AUG (methionine)
start codon
UAA, UGA, UAG
stop codons are
Gene expression
DNA -> mRNA -> Protein -> trait
Site of replication in eukaryotes
nucleus
The site of translation
cytoplasm and ribosomes
point mutation in which one nitrogeneous base (nucleotide) is changed to another
substitution mutation
a mutation in which a nucleotide is added to a DNA sequence in a gene
insertion mutation
a mutation in which a nucleotide is removed from a DNA sequence in a gene
deletion mutation
point mutation
a mutation affecting only one or very few nucleotides in a gene sequence.
frameshift mutation
mutation that involves the insertion or deletion of a nucleotide in the DNA sequence; all of the nucleotides are shifted after the change
Why are cells so small?
smaller cells are more efficient because they have more surface area across which to pass oxygen, nutrients and waste materials
3 parts of a nucleotide are
sugar, phosphate, nitrogen base
The structure of a DNA molecule can be described as a…
Double stranded helix, 2 strands of nucleotides: phosphate group and sugar (deoxyribose) form the “backbone”, and the nitrogenous bases (A-T, C-G) form the “rungs” of the ladder, weak hydrogen bonds hold the 2 nitrogen bases together
Rule of complementary base pairing
A and T form a base pair and C and G form a base pair
Why does DNA replicate?
for cellular division: reproduce, growth, and repair
The process in which DNA makes a duplicate copy of itself. (DNA to DNA)
DNA replication
Step one of DNA replication
DNA is unzipped by enzyme DNA helicase
Step two of DNA replication
Free-floating nucleotides are joined to the original DNA strand by DNA polymerase, this builds the new strand
End result of DNA replication
two identical DNA molecules are made; called: semi-conservative replication because each copy has 1 original strand and 1 new strand.
name of DNA
deoxyribonucleic acid
name of RNA
ribonucleic acid
sugar of DNA
deoxyribose
sugar of RNA
ribose
Is RNA single or double stranded?
single stranded
Is DNA single or double stranded?
double stranded
Nitrogenous bases in DNA
Adenine, Thymine, Cytosine, Guanine
Nitrogen base in RNA but not DNA
Uracil
protein synthesis
the formation of proteins by using information contained in DNA and carried by mRNA
