7B Flashcards
- What are the components of DNA and its three-dimensional structure?
C-3
S-6
Components: PO4, deoxyribose, nitrogenous base. Structure: double stranded, double helix, antiparallel, twisted ladder, side of sugar and PO4 (backbone), rungs H bonds between nucleotides
- State the Chargaff’s rul
- The amounts of thymine and adenine in DNA are the same and the amounts of cytosine and guanin are the same (A=T, G=C). 2. The proportion of adenine and gunaine differs among species.
- What evidence enabled Watson and Crick to decipher the structure of DNA?
Rosalind Franklin’s research in x-ray crystallography revealed the shape of DNA molecule: alpha helix. (final piece of evidence.
- Explain how hydrogen bonds contribute to the structure of DNA.
Connect complementary bases forming the “rungs” of the DNA twisted ladder structure. Strengthen DNA.
- Explain the roles of DNA, RNA, and protein in the central dogma.
Gene expression: A multistep process including transcription and translation, by which genetic information encoded by a gene is converted into a structural or functional part of a cell or body. DNA—>transcribed into mRNA—> translated into Protein.
- Describe the structural differences between RNA and DNA.
4
Single vs. double strand, Uracil instead of Thymine, Ribose vs. Deoxyribose, RNA smaller than DNA.
- Describe the functional differences between RNA and DNA.
DNA: stores RNA/protein encoding information, transfers information to next generation of cells. RNA: carries protein-encoding information, helps to make proteins, catalyzes some reactions.
How does mRNA contribute to protein synthesis?
Carries the information that specifies a protein. Has the information in the form of codons (genetic code word that corresponds to one amino acid.)
How does rRNA contribute to protein synthesis?
3
Main component of ribosomes where polypeptide chains are built. Correctly aligns ribosome and mRNA, catalyzes the formation of peptide bonds between amino acids.
How does tRNA contribute to protein synthesis?
A “connector”, binds an mRNA codon at one end and a specific amino acid at the other. Delivers the amino acid to the ribosome at the correct spot along the mRNA molecule.
- Where in the cell does transcription occur?
Nucleus
What is the role of RNA polymerase in transcription?
Def: Enzyme that uses a DNA template to produce a molecule of RNA. (builds the RNA chain) A catalyst!
What are the stages of transcription?
Initiation, elongation, termination
What happens during the Initiation stage of transcription?
In the Initiation phase, enzymes unzip the DNA double helix exposing the template strand. RNA polymerase then attaches to a promoter (a DNA sequence that signals the gene’s start.)
What happens during the Elongaton stage of transcription?
In elongation, RNA polymerase moves over the gene in a 3’ to 5’ direction, unwinds the DNA helix, reads the base sequence, and joins free RNA nucleotides into a complemetary strand of mRNA.