Module 2-4 Flashcards
Structure of nucleotides
A nitrogen base
Ribose (5 carbon sugar)
A phosphate group
What are the two nitrogen base categories?
Purines -have 2 rings (Adenine & Guanine are Purines)
Pyrimidines -have one ring (Cytosine, Uracil, and Thymine are Pyrimidines)
What are the two ribose?
Ribose (RNA)
2-deoxyribose (DNA)
What are 5’ and 3’
These are labeled carbons in rivose, 5’ end it where phosphate is attached
What are phosphates?
In DNA, phosphates are the “sugar-phosphate backbone”
What is step 1 of the DNA strand formation?
A nucleotide is added to the 3’ of an existing chain.
Its phosphate binds to the oxygen on the 3’ sugar
What is step 2 of the DNA strand formation?
A diphosphate is formed as a byproduct
What is step 3 of the DNA strand formation
A phosphodiester bond is formed between the new nucleotide and the existing strand of DNA
What direction are nucleotides attached?
5’ to 3’
Why does DNA form a double helix?
Nitrogen bases are hydrophobic
Phosphate backbone is hydrophilic
What are genes?
Small pieces of DNA that contain information to make a protein. (Coding DNA)
What amount of a gene is used to make protein?
Most of a gene isn’t used
Who solved the structure of DNA?
James Watson & Francis Crick
What is the fundamental structural unit of DNA?
Deoxyribonucleotides
What is RNA?
RNA is a nucleic acid similar to DNA, primarily tells the cell what kinds of proteins to make
Structural differences of DNA and RNA.
RNA uses Uracil instead of Thymine
RNA uses ribose instead of deoxyribose
RNA is single-stranded, therefore it is less stable
What are the 3 types of RNA?
Messenger (mRNA)
Transfer (tRNA)
Ribosomal (rRNA)
What does mRNA do?
carries instructions to making protein in the cell
What does tRNA do?
tRNA brings amino acids to ribosomes to build protein
What does rRNA do?
rRNA is a part of ribosomes
What are the 5 levels of DNA packaging
- Double Helix
- Nucleosomes (beads on a string)
- Chromatin fiber
- Looped domains
- a) Folded looped domains
- b) Chromosomes
What is the central dogma?
A set of principles that explain how DNA contains instructions for building RNA & Proteins
What are the 3 components of the central dogma?
- Replication (DNA -> DNA)
- Transcription (DNA -> RNA)
- Translation (RNA -> Protein)
What is DNA replication?
DNA is copied during cell division, the major enzyme is DNA polymerase
What is DNA transcription?
A section of DNA info is transcribed into RNA so the info can leave the nucleus, the major enzyme is RNA polymerase
What is RNA translation?
RNA is read and translated to produce proteins, the major enzymes are ribosomes
When is DNA most vulnerable?
During replication. Bonds are broken
Why is DNA replication semi-conservative
The original strand is conserved
What are the 4 steps of DNA replication?
- Unwinding the DNA
- RNA primers bind to unwound strands
- Elongation
- Termination
How is DNA unwound?
DNA helicase unwinds the 2 strands
What enzyme allows for DNA replication to begin?
Primase
What enzyme copies single strands of DNA?
DNA polymerase
What direction does DNA polymerase move
3’ -> 5’
What are the Okazaki fragments?
OFs are fragments of DNA synthesized off of primers on the lagging strand
What joins the Okazaki fragments?
Ligase
What prevents DNA shortening at the end of the replication
Telomeres, which are attached with telomerase
