52 terms

Biology Unit 5

Who was credited with discovering the structure of DNA and when?
John Watson and Crick in 1953-stole idea from Franklin's pictures and did not give her any credit
Friedrich Miescher
first to isolate and identify DNA from nucleic acids and suggested it had a role in hereditary in 1871
Erwin Chargaff
A=T C=G in 1950
what does DNA stand for?
Deoxyribose nucleic acid
What makes up nucleotides?
a phosphate group, a 5-carbon sugar "Deoxyribose", and 1 of 4 nitrogen contain bases (A,T,C, or G)
What are the 4 nitrogen bases?
Adenine, Thymine, Cytosine, and Guanine.
What are complementary base pairs and what holds them together?
A=T and C=G and joins two strands of DNA together and are held together by hydrogen bonds which are weak enough to pull apart (unzip)
the double helix
the structure of DNA. a "twisted ladder"
contains 2 parts-backbone-sugar and phosphate goups. and steps, which are the nitrogen bases. the nitrogen bases are held together by hydrogen bonds (watson and Crick)
How does 6ft of DNA fit into each and every cell?
within each cell (eukaryotic) there is a nucleus and within the nucleus there are chromosomes. within the chromosomes, there is chromatin, which is a thread wound together to fit into chromosomes. then there are nucleosomes which is DNA wrapped around histones, which are little dots that we see and the proteins. Finally, this is all compacted into a double helix. the nucleosomes are packed into the chromatin
protein molecules around which DNA is tightly coiled in chromatin. little dots
substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones
bead-like structure in eukaryotic chromatin, composed of a short length of DNA wrapped around a core of histone proteins
DNA replication steps
1) Enzymes "unzip" the base pairs, unwinding the DNA double helix
2) Free DNA nucleotides find their complementary base pairs along the new strands
3)DNA polymerase (an enzyme) helps assemble the sugar-phosphate backbone to complete the new DNA strands, putting it all back together.
DNA semi-conservative process
The new molecules of DNA are identical to the original DNA. the DNA keeps one old strand and makes a complementary new one, making it semi-conservative.
How is DNA copied?
in the S phase of interphase
Where does DNA replication occur?
in the nucleus of a cell
why does DNA replication occur?
for cell division-growth, repair, and asexual reproduction
General function of DNA
it is an organism's blue print. It tells your cells what proteins they need to make in order to determine what traits and characteristics you and all organisms have. DNA molecules provide instructions for assembling protein molecules and that is virtually the same mechanism for all life forms. ex-us, whales, plants, all have DNA that makes us look the way we do.
What is the structure of DNA from Simple to complex (or complex to simple)
cell, nucleus, chromosomes, chromatin, nucleosomes, histones, DNA (double helix)
what are genes?
regions of DNA that code for proteins which determine traits! ex-if you have a protein that makes brown eyes, you will have brown eyes
General Function of RNA (ribonucleic acid)
it is a copied, single stranded form of DNA that acts as a messenger by carrying the DNA message from the nucleus to the ribosomes in the cytoplasm. it solves the problem of DNA being damaged if it leaves the nucleus.
what is the purpose of transcription?
it translates the language of DNA to RNA so a message can be carried to the ribosomes and is the first step of making a protein
Transcription Process
1)DNA unzips:enzymes split apart base pairs and unwind the DNA double helix
2)Bases pair up-Free RNA nucleotides pair up ith their complementary basses along the DNA
3)New backbone is formed-the sugar-phosphate group backbone is assembled to complete the RNA strand and separates from the DNA. the mRNA breaks away and the DNA rezips.
What is mRNA
the message that is formed during transcription that goes to the ribosomes
What bases appear in transcription?
A,C,U,G--->all a's pair up with U's and U's pair up with A's.
transcribe this: A T G G A C T T A G C A
Compare the purpose of DNA replication and RNA transcription
DNA-occurs for cell division
RNA-occurs for the synthesis of proteins
Compare the location of DNA replication and RNA transcription
both occur in the nucleus
Compare how the processes of DNA replication and RNA transcription occur
1)DNA unzips (For both)
2 DNA) free DNA nitrogen bases pair up and 2 RNA) free RNA bases find pairs
Compare the outcome of DNA replication and RNA transcription
DNA-2 identical double-stranded molecules
RNA-1 mRNA single-stranded molecule
purpose of translation
the message carried on the mRNA is translated at the ribosomes to an amino acid sequence using tRNA
purpose of mRNA
carries a message from the DNA in the nucleus to the ribosomes that is later translated into amino acids
purpose of tRNA
transfer molecule-carries an amino acid that will match up the appropriate mRNA codon, building a protein. translates the mRNA to an amino acid language
set of three nucleotide sections of mRNA. there are 20 amino acids and only 4 bases so each 3-nucleotide combo codes for one amino acid
group of three bases on a tRNA molecule that are complementary to an mRNA codon and are matched with the codon so the correct amino acid is made
amino acids
proteins that are made as a result of translation when the codons are matched up they start to build up a strand of proteins
changes in the genetic material. happens when cells make mistakes in replicating or transcribing their own DNA
point mutation
single-base changes. 1 nucleotide is changed in a gene's DNA sequence. this can be a missense, nonsense, or silent mutation.
result in a single amino acid change within a protein. this does change the resulting protein. EX if codon was CCC and was changed to TCC the mRNA would be transcribed as ACC instead of GGG resulting in serine over glycine.
create a premature stop codon causing the protein to be shortened. this does change the resulting protein. ex- is AAC and then changed to ATC, then the mRNA would read UAG which is a stop
change the DNA sequence but not the amino acid sequence. this does not change the resulting protein and has no effect on an organism. there are multiple combos on the genetic code to get to certain amino acids. ex- if CCC then changed to CCA, would transcribe to GGU which would be glycine and so is GGG.
Frameshift mutation
result from the insertion or deletion of one or more bases into or from the DNA sequence. this alters the grouping of nucleotides into three base codons causing a shift in the "reading frame" during translation. this resulting protein is normally nonfunctional.
an additional nucleotide is read. ex- if TAC-TTC and an A was added before second T, then it would be TAC-ATC, changing the results
a nucleotide is deleted in the sequence causing a shift. ex0 if TAC-TTC, and A was deleted, would be TCT-TC, causing a change.
are things that can cause a change in a DNA sequence. ex-UV light, radiation, exposure to chemicals.
pros and cons of mutations
altered genes will pass on to every cell that develops from it.
pros-source of genetic variability in species
cons-can disrupt normal biological activity resulting in a genetic disorder or cancer.
what molecules are involved with transcription?
What molecules are involved with translation?
rRNA, mRNA, tRNA, amino acids
how does sickle cell anemia relate to form determines function/consistency and change
FDF-the hemoglobin cell is normally circular allowing oxygen to be carried to red blood cells. when it is mutated. the hemoglobin is a sickle shape and can hook on to others causing clots.
CC-still have the function of bringing oxygen to red blood cells but change into a different shape.
how does PKU relate to energy flows and matter cycles?
normal PAH is supposed to transform phenylalanine into essential compounds for the body to use uses energy to transform and the phen. is continually cycled along with the essential compounds. mutated PAH does not cycle and just builds up stopping the flow,
what is rRNA
the RNA that makes up the ribosomes where proteins are assembled
how are mutagens harmful?
They can increase mutations and the chance of cancer or uncontrolled cell divison