unit 4 Flashcards
nucleic acids
the macromolecule that holds genetic materical (DNA)
contains genes
genes
sections of dna that serves as instructions for making proteins
nucleotides
what is the structure and laber
makes up nucleic acids
three parts: sugar phosphate nitrogen base
sugar: deoxyribose, ribose
phosphate
nitrogen base: Adenine, Guanine, Cytosine, Thymine (DNA ONLY), Uracil (RNA only)
draw sgtructure
dna structure - bonds in dna
double helix: a twisted ladder shape
nitrogen bases bond in the middle with weak hydrogen bonds, all other bonds are covalent bonds
contemporary base rule
nitrogen bases bond only to their contemporary base pair
A&T
C&G
dna is _____
antiparallel
the strands run opposite directions
purines
A or G
pyrimidines
C AND T
deoxyribose is alway the __ end
3’
phosphate end is always the __ end
5’
RNA structure
single strand of nucleotides with exposes bases
A&U C&G
chromosomes
tightly coiled strands of DNA
why does a cell do DNA replication?
when a cell is ready to divide, it must first copy its DNA, so when the cell does divide the cells have the same amount of DNA and can be copied again
when and where does DNA rep happen
nuclues, S phase
steps of DNA rep
Helicase unzips the DNA at the origins of replication.
- Primase creates short RNA primers for DNA polymerase to
know where to start.
DNA Polymerase pairs complementary nucleotides and bind them according to the base-pairing rules (A-T and C-G), working in the 5’ to 3’ direction only (using the 3’ to 5’ strand as
the template).
the leading strand is made towards the replication fork, thus only needs 1 RNA primer to get started and can be made continuously.
the lagging strand is made away from the replication fork, thus needs multiple RNA primers and it creates okazaki fragments which are short pieces of DNA that r later joined together by DNA ligase
DNA Ligase then comes in to seal the gaps in DN
RNA primers r removed and replaced with DNA by DNA polymerase. and it double checks everythign
Two identical DNA molecules are formed, each with an old Strand and New Strand
what is protein synthesis
The process of reading the instructions in DNA to make a polypeptide
polypeptide
a chain of aminto acids thats can bind to others and fold into proteins
central dogma of genetics
DNA -> RNA -> Protein
transcription, translation
transcription steps - Protein Synthesis
location: nucleus
- RNA Polymerase binds to DNA promoter and unzips the gene that
needs to be copied. - RNA Polymerase pairs nucleotides based on the RNA base pairing rules
(A-U and C-G). - Release completed mRNA molecule.
- DNA zips up and mRNA leaves the nucleus.
what is dna’s purpose
to make proteins
translation
This happens in ribosomes,
- mRNA attaches to a ribosome.
- Ribosome reads the mRNA codons, always in the 5’ to 3’ direction, starting at AUG.
- tRNAs deliver amino acids based on the mRNA instructions.
- Continues to drop of a.a. and the ribosome binds them together with peptide bonds until a stop codon is reached and the polypeptide chain is
released.
Post transcriptions modifications
Your transcription RNA splicing occurs which is when introns are removed and exons are spliced together which edits the gene.
A Gcap is added to a 5 Prime end which facilitates binding to a ribosome then poly a tail is added to the three prime end to help the mRNA leave the nucleus
nucleic acids
The macromolecule that holds our genetic materia
Nucleotide
- The monomer of nucleic acids
Chromosome
- Tightly coiled strand of DNA that contains genes
Gene
A section of DNA (and thus of a chromosome) that has instructions to code for a protein
RNA primer
- Short piece of RNA used to help get the DNA polymerase
started
- Okazaki fragments
- Short pieces of DNA created from the discontinuous replication
of the lagging strand
Use a Venn diagram to compare and contrast DNA
and RNA.
DNA-
* Deoxyribose
sugar
* Thymine
* Double helix
* Doesn’t leave
the nucleus
RNA-
* Ribose sugar
* Uracil
* Single strand
* Can leave the
nucleus and
go into
cytoplasm
Both-
* Made of
nucleotides
* Adenine,
Cytosine,
Guanine
complementary base pairing rules
- A always binds with T
- C always binds with G
Explain, in detail, the structure of a DNA molecule.
- DNA is a double helix, a twisted ladder composed of two complementary strands that are antiparallel (one runs 3’ to 5’, the other 5’ to 3’).
- The outside is composed of sugar and phosphate
backbone held together by covalent bonds. - The inside rungs are nitrogen base pairs
held together by weak hydrogen bonds.
Why is DNA rep important?
- This process is significant because it happens during the S phase of Interphase before the cell divides to ensure that each resulting daughter cell has all of the genetic information.
Explain why DNA replication is considered to be
semi-conservative.
- This is because each parent strand is used as a template for the new complementary strand
thus the end result is 2 identical DNA molecules that are half “old” and half “new”,
thus part of the molecule is “semi-conserved”.
*Transcription
The process of copying DNA into a complementary strand
of mRNA that can carry the instructions out of the nucleus
introns
Non-coding regions of mRNA that must be removed
exons
Coding regions of mRNA that will be spliced together
genetic code
Code of instructions for how to make proteins
codon
A set of 3 nucleotides on mRNA
Anticodon
Complementary 3 nucleotides on tRNA
- Amino acid =
- The monomer of proteins, linked together with peptide bonds to
form a polypeptide
translation
- The process of interpreting the message on mRNA into a
polypeptide to make a protein
Epigenetics
- The study of changes in gene expression that are heritable
why is a two-step process
is necessary in order to make proteins.
DNA can’t leave the nucleus, and it holds the instructions for making proteins.
Thus a copy of it must be made that can leave the nucleus (mRNA during transcription).
Then those instructions can be translated to assemble the polypeptide chain (translation).
transscription steps
location: nucleus
- RNA Polymerase binds to DNA promoter and unzips the gene that
needs to be copied. - RNA Polymerase pairs nucleotides based on the RNA base pairing rules
(A-U and C-G). - Release completed mRNA molecule.
- DNA zips up and mRNA leaves the nucleus.
Describe an example of how gene expression is
regulated.
- Regulatory proteins called transcription factors control
gene activity by controlling the amount of transcription. - Repressors decrease transcription.
- Activators increase transcription
Explain the difference between epigenetics and
mutations.
Both are heritable, but mutations change the actual DNA
sequence, whereas epigenetics do NOT change the DNA
sequence, just how that DNA sequence gets expressed.
