DNA’s monomer and what she made of
nucleotides -sugar -phosphate -nitrogenous base (adenine, thymine, guanie, cytosine) eSPN
polymer and structure
DNA -double helix -bases held by hydrogen bond complimentary base pairing (A-T) (C-G)
Purines
double ring (A and G)
Pyrimidines
single ring (T and C)
two DNA strands are ____
antiparallel
5’ and 3’
difference in DNA and RNA
RNA…
- uses sugar ribose instead of deoxyribose
- has brasil instead of thymine
- Single stranded
DNA Replication
- process of copying one DNA double helix into 2 identical double helices
- S PHASE
DNA replication is semi-conservative
- bc a new double helix has one old strand and one new strand
- parents and daughter DNA molecules are identical
steps of DNA replication
- strand starts out hydrogen bonded
- DNA HELICASE unwinds and “unzips”
the double-stranded DNA - DNA POLYMERASE uses complementary base pairings to PUT/PLACES nucleotides
- DNA LIGASE LINKS any breaks in the sugar-phosphate backbone like GLUE
- The two double helix molecules are identical to each other and the OG DNA
Gene Expression
-process of using information within a gene to synthesize a protein is called gene expression
parts of gene expression
- Transcription
2. Translation
Transcritption
-located in nucleus
-“rewrite”
-DNA–>mRNA
-DNA serves as a templet for mRNA
-
RNA POLYMERASE (enzyme) in transcription
binds to promoter (region of DNA that contains of special sequence of nucleotides) and adds complementary RNA nucleotides (U instead of T)
-RNA polymerase stops at terminator
mRNA Processing
- some info isn’t needed for the final product
- introns=intrude; stuff you don’t need–>cut them out
- entrons=expressed, needed
- add guanine cap and Poly-A tail (signal so they know what to do)
- mature mRNA–>go to translation
codon
- three base sequence in mRNA that during translation directs the addition of an amino acid to a protein or directs termination of a process
- triplet codes (AAG)
Translation
- mRNA–>protein
- -cytoplasm at ribosome
- completely different language
- mRNA has a codon
- tRNA: anticodon (complementary base to codon), transfer amino acids
there are __ possible codons, but only ___different tRNA molecules because of the ___
64; 40
-wobble effect, which states that for some tRNAs, the third nucleotide in the mRNA codon may vary
1st step of translation
initiation:
- tRNA attaches to start codon (AUG)!!!
- ribosome has 3 bonding sites for tRNAs—>P (peptide site),
2nd step of translaion
Elongation: -polypeptide grows -tRNA moves through A, P, and E sites (translocation) A=amino acid site P= peptide site E=exit site for tRNA
3rd step of Translation
Termination:
- stop codon we done
- all parts separate
gene mutations
permanet change in the sequence of bases of in DNA
-mutations that occur in sex cells may be passed down from generation to generation
sex cells
germ cells
mutations in the remainder of the cells of the body
somatic cells
causes of mutations
- errors in replication
- Mutagens
- transposons
- viruses
-errors in replication:
DNA polymerase doesn’t proofread v well
-Mutagens:
environmental influences (radioactive elements, UV radiation) and certain organic chemicals (chemicals in cig smoke and pesticides)
transponsons
- specific DNA sequences that have the remarkable ability to move within and between chromosomes, and their movement and new location can sometimes alter the neighboring genes, increasing and decreasing their expression
- jumping genes, sketch
tRNA
transfers animo acids to the ribosome
Viruses
can insert their own DNA in ours, copying virus
Point mutations
- base subsitution (A instead of T)
- outcomes
1. change in amino acid
2. silent mutation; usually on your last letter, nothing really happens; worse to switch first letter
3. Abnormal protein (sickle cell)
4. incomplete protein
Frameshift
- addition
- deletion
- outcome: nonfunctional protein ALWAYS!
characteristics of cancer cells
- genetically unstable
- do not correctly regulate the cell cycle
- escape the signals for cell death
- can survive and proliferate elsewhere in the body (metastasis)