DNA functions summative

what is the outcome of transcription?

• RNA polymerase reaches the terminator, GGCC, which causes the release of DNA and new RNA and ends transcription

• RNA (mRNA) stays inside, DNA leaves nucleus

what is the difference between RNA and DNA?

• base pairs, RNA = A —> , DNA = A —> A

• RNA has a major role in protein synthesis

• where theyre found/where they stay

what are the similarities between RNA and DNA?

• both organic compound family of nucleic acids

• nucleotides as building blocks

• carry information to help make proteins

what is the role of complementary base pairing during transcription?

• to allow the coding strand to bind w/ the template strand

• assures accurate transfer of genetic information from DNA to mRNA/RNA

template strand of DNA

3’ —> 5’

• read by RNA polymerase to create mRNA

• used in both transcribing/translating

• starts w/ AUG (start codon), ends w/ GGCC (terminator)

coding strand of DNA

5’ —> 3’

• not used during transcription

role of mRNA during translation

• messenger RNA, which carries the instructions for making proteins

role of tRNA during translation

• transfer RNA, which reads the instructions for making proteins and moves/places amino acids in the correct order/position

role of rRNA during translation

• part of ribosome, makes proteins

how is information encoded in DNA?

• through base pairing

DNA base pairings —> C/G , A/T

what is the outcome of translation?

• creation of polypeptide chain, which folds into a functional protein

• ribosomes separate into subunits

• mRNA released

transcribing a strand of DNA (step 1)

• transcribe the CODING strand, and keep everything the same besides the Ts (which become Us)

• ignore the TATA and GGCC boxes

translating a strand of DNA (step 2)

• translate the TEMPLATE strand and start with AUG and then do the base pairs of the thing you transcribed earlier

ex. Met, his, pro (full names)

• translation ALWAYS starts with met/methionine

what are the roles of complementary base pairings in translation?

• ensures that there is an accurate translation of genetic material from DNA to RNA and from RNA to proteins

• ribosomes use mRNA as a template to guide assembly of amino acids into proteins, which follows from codon/anti codon complementary base pairing rule

• allows information encoded into RNA to be stored in a single strand

transcription initiation

• starts w/ the promoter after RNA polymerase binds to it

• TATA box

transcription termination

• ends w/ terminator after RNA polymerase reaches the terminator (GGCC), which releases DNA and new RNA

translation initiation

• start codon (AUG)

translation termination

• when polypeptide chain is formed, ribosome sub units and mRNA is released

• stop codon

polypeptide chain v protein

polypeptide chain - long chain of amino acids

proteins - work based on their form, made up of amino acids

what determines the function/structure of a protein?

sequence of amino acids —> how a protein folds —> determines shape —> determines function of a protein

mis sense mutation

• same CCC —> CAC (swap), substituion of an amino acid for another

ex. sickle cell anemia

non sense mutation

• stop CGA —> TGA (stop)

ex. CAG changes to UAG codon which results in termination of translation

silent mutation

• synonyms CCC —> CCA

• no effect on protein sequence

ex. tumor suppressors, which may lead to cancer cells

how does the change in a single base pair lead to a change in the function of the protein produced?

• frame shifts (caused by deletion)

• DNA mutations (caused by spontaneous, (inside factors) or induced (outside))

chromosomal mutation

• affects MANY genes (number of chromosomes increase/decrease in genome, change in structure)

• duplication, extra copies of genes

why/how does chromosomal mutations occur

• b/c of a change in chromosome structure

• errors in crossing over/cell division

what is the severity of a single base insertion/deletion and the result of the polypeptide change?

Insertion: extra base(s), causes frame shift

Deletion: genetic material breaks off, causes frame shift

(ppc) Polypeptide chain: frame shift happens if there is an insertion/deletion of amino acid bases, which affects the ppc 

Evidence to support that not all mutations are bad 

Benefit - some can help w/ chronic pain, unbreakable bones, immune to malaria, lower # cholesterol, rely on little sleep, run faster, see more colors, etc

• Controls muscle growth, less body fat

• CCR5 (disease resistance), which affects immune system and blocks some viruses like HIV

ACTN3 (speed gene)

• Found in fast twitch muscles

• Helps w/ speed and power 

Neutral - doesnt harm/benefit indivudal

Harmful - if protein changes, can lead to more mutations which may lead to cancer cells ex. Breast cancer usually 13% → up to 70% w/ BRCA1 mutation

Importance of controlling gene expression

• b/c there would be a waste of resources w/o it

• Helps NOT create harmful things in the body (like stomach acid in your eyes), wrong things going in certain areas of the body

• Not every cell needs every gene, only use gene w/ their specific function 

Diagram of gene expression

DNA → mRNA → polypeptide chain → protein

An example of how a gene may be regulated

• Regulators binding to a promoter to help RNA polymerase start transcription or having rpressors bind to it so transcription doesnt happen/is halted

• Able to bind w/ enhancer sequences (based on type), which increase transcription

• Can bend DNA to bring the promoter/enhancer closer

Epigenetics and what its used for

Epigenetics: changes in gene expression that is caused by mechanisms other than changes in DNA (genetic code)

• series of chemicals that sit on top of a genome and cause DNA to be more tightly bound to histones,reducing gene expression

OR

• To be more loosely bound leading to greater gene expression 

• Changes w/ twins

Value of identical twins in the function of genes

• Same genes

• Generally same functions of genes, which can change over time (epigenetics)