Unit 9 - DNA, RNA, and Biotechnology

DNA (deoxyribonucleic acid) structure

DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds

DNA monomers

nucleotide: adenine, thymine, guanine, cytosine

Nucleotide structure

5 carbon sugar, phosphate group, nitrogenous base

DNA template strand -> complementary strand base pairing rules

A = T C = G

RNA (ribonucleic acid) structure

single stranded chain of nucleotides

RNA monomers

nucleotides: adenine, uracil, guanine, cytosine

Transcription

process of making RNA using RNA polymerase, the DNA template strand is copied to make RNA

Transcription base pairing rules

A = U C = G

mRNA

carries the message from the DNA to the ribosome; made in the nucleus, and then goes to the cytoplasm/ribosomes

tRNA

brings the amino acid to the ribosome for the growing polypeptide/protein; made in the nucleus, and the goes to the cytoplasm

rRNA

works with other proteins to make up the ribosomes; made in the nucleolus within the nucleus

Protein structure and function

They are made up of chains of amino acids. They have many functions such as structural support and enzymes.

Translation

the RNA is read in groups of three bases or codons and each codon codes for a specific amino acid, this process makes proteins

1st step of translation

The small ribosomal subunit attaches to the mRNA and searches for the start codon (AUG)

2nd step of translation

The tRNA with the anticodon to the AUG will attach

3rd step of translation

the large ribosomal subunit will attach so the start codon is in the p-site

4th step of translation

The next complementary tRNA will attach to the next codon in the a-site

5th step of translation

A bond will be formed between the amino acids in the chain

6th step of translation

The ribosome will shift down to the next codon. What was in the p-site moves the the e-site, and what was in the a-site enters the p-site.

7th step of translation

The process continues until a stop codon enters the a-site, and then the ribosome stops and detaches from the mRNA.

What are mutations?

Heritable changes in DNA. They tend to have the greatest effect on a gene when they are early on in the coding.

Point mutation

the substitution of a base in the DNA

Frameshift mutation

the insertion or deletion of a base, it changes the entire reading frame for all the codons from the point of mutation. They have the biggest effect on a protein when it inserts or deletes 1 or 2 bases.

Silent mutation

no change in the amino acid sequence

Missense mutation

changes an amino acid in the protein

Nonsense mutation

early stop codon

BLAST database

online database that is used to identify unknown DNA/protein sequences

Gel electrophoresis

used to separate molecules or fragments based on their charge and size

Restriction enzymes

enzyme that cuts DNA at a specific sequence of nucleotides

Restriction site

a specific sequence on a DNA strand that is recognized as a cut site by a restriction enzyme

Blunt ends

fragment ends of a DNA molecule that are fully base paired

Sticky ends

the uneven ends of a double-stranded DNA molecule that has been cut with a restriction enzyme

What kind of ends are used to make recombinant DNA?

Sticky ends are used because they can fit together with complementary ends.

DNA ligase

An enzyme that reforms the bonds between nucleotides. Those bonds are broken by restriction enzymes.

Recombinant DNA

DNA made from two different sources joined together

What is PCR used for?

It is used to find a specific sequence of base pairs, and make copies of it.

Five ingredients of PCR mixture

DNA template, DNA primers, Taq polymerase, dNTPs, buffer

Denaturation (PCR step 1)

In this stage the temperature is raised to 95℃, and the two complementary strands of DNA are separated.

Annealing (PCR step 2)

In this step the temperature is lowered to 50 - 65℃, and it specifies the region of DNA to be copied.

Extension

In this stage the temperature is raised again to 72℃, and the DNA is copied using Taq DNA polymerase.

Primers

The short single stranded pieces of DNA that are complementary to the original DNA sequence

dNTPs

The nucleotides that are added by the polymerase

Taq DNA polymerase

The special kind of nucleotide that is used in PCR, it is used because it is able to withstand the high temperatures

CRISPR-Cas9 use

a unique technology that enables geneticists and medical researchers to edit parts of the genome by removing, adding or altering sections of the DNA sequence

DNA Fingerprinting/profiling use

a technique used to compare DNA from different sources

STRs

Short tandem repeats that help to identify the different DNA sources

The DNA in eukaryotes

Eukaryotes have multiple chromosomes in the nucleus and they are linear

DNA in prokaryotes

Prokaryotes have one circular chromosome and have plasmids

Plasmids

circular DNA found inside of bacteria, they are non-coding

Bacterial transformation

Bacterial transformation is a technique used to produce multiple copies of a recombinant DNA molecule