What is a nucleotide?
Units of a long molecule that make up DNA; their sequence carries the genetic information of an organism
Nucleotide is made of ...
1) Sugar (Deoxyribose)
2) Phosphate (phosphoric acid)
3) Nitrogen base (A, G, C, T)
Function of a nucleotide...
- Genetic info with structures for making proteins
- Every organism is composed of the same four nucleotides
How does replication take place? (steps of replication are...)
1) Ladder untwists
2) Ladder unzips
3) Left forms a new right side by base pairing
4) Right forms a new left side by base pairing
5) Ladder zips and twists
Nucleotide structure in RNA
1) Sugar = ribose
2) Phosphate = phosphoric acid
3) Nitrogen bases are A, U, G, C
Differences/Similarities between DNA and RNA nucleotides/structure
1) DNA is double stranded and RNA is single
2) Sugar of DNA is deoxyribose, sugar of RNA is ribose
3) Nitrogen bases of DNA are A, T, G, C and bases of RNA are A, U, G, C
- Short folded strand with 3 bases
- Function: read the code from mRNA and collect the correct amino acids to build a protein
- Hamburger bun shaped
- Helps build ribosome that will assemble protein (like part of the factory)
The steps of transcription are...
1) DNA untwists and unzips
2) RNA forms from one side of the DNA (template) by base pairing
3) RNA detaches and leaves nucleus
4) DNA zips up and twists
During transcription, if the DNA template was ACCAACCGAGT, it would be transcribed to...
Because there are 4 different bases (A, U, G, C), there __(#?)__ triplets, which are called _____.
64 triplets that are called codons
An overview of protein synthesis...
1) In the nucleus, DNA→mRNA (transcription)
2) mRNA leaves nucleus and goes through cytoplasm to find a ribosome
3) Anticodon of tRNA matches with codon of mRNA to form an amino acid chain → protein (translation)
Translation is to convert from language of _____ into the language of _____.
from language of nucleic acid into language of amino acid
Steps of Translation
1) mRNA leaves the nucleus and travels through cytoplasm to a ribosome
2) mRNA "shares" the code of tRnA
3) tRNA translates code and collets the proper amino acid and brings it to ribosome
4) Ribosome joins amino acids to make protein
point mutation/substitution affects protein
one base is changed to another, affects usually no more than a single amino acid
What is a frameshift mutation?
When a single base pair is added or deleted and the bases are still read in groups of 3, but the groupings are shifted for every codon that follows; shift of the "reading frame"
insertion/deletion affects protein synthesis...
base inserted or removed from the DNA sequence and thus every base after the first "wrong" one is also wrong because it is shifted (every codon after deletion or insertion will be affected)
A chromosomal mutation is...
Chromosomes break, get lost, rejoin incorrectly--> a mutation that involves a change in the number or structure of chromosomes; can change the locations of genes on chromosome; possibly could change the number of copies of some genes
Four types of chromosomal mutations...
additions/insertions (would both cause frameshift mutations)
inversions (breaks off, flips, and rejoins incorrectly)
Translocation (breaks off of one chromosome and is added to another)