Human Bio year 11 Chapter 9: DNA + Genes

what is DNA:

a molecule found in almost all cells that carries genetic instructions for cell structure and function

where is DNA located:

in the nucleus for nuclear DNA or in the mitochondrion for mitochondrial DNA

what is the structure of DNA:

double Helix structure made up of a chain of repeating units called nucleotides

what are the three parts of a nucleotide:

phosphate group, a sugar molecule and one of the four nitrogenous bases

What is mitochondrial DNA:

a circular molecule that plays an important role in coding for transfer RNA and enzymes needed for cellular respiration

What is the purpose of DNA replication:

to create 2 identical copies of DNA for processes like mitosis where it creates 2 identical daughter cells

what does helicase do in DNA replication

unwinds the double Helix structure and separates the strands (like scissors cutting down the middle) it does this by breaking the hydrogen bonds that exist between complementary base pairs, the two separated strands can then act as templates for the synthesis of new complementary strands

what does DNA polymerase do in DNA replication:

synthesis/creates new strands from the two parental template strands by aligning floating nuclear tides (in the cell) to their opposite complimentary base partner, overall creating a new strand of DNA.

What is a protein:

a large complex molecule made up of one or more long chains of amino acids.

What is the function of proteins:

They can form transport structures cell structures enzymes for specific tasks and protect the body etc.

What is protein synthesis:

the process by which cells build proteins, through transcription and translation

what are the 2 main stages of protein synthesis:

transcription and translation

What are the four main stages of transcription:

unwinding the DNA, making mRNA, processing mRNA, MRNA to ribosome

In transcription what happens during the first step, unwinding the DNA:

chemical messengers that enter the nucleus from the cytosol bind to DNA triggering the enzyme RNA polymerase to begin the process of making messenger RNA. The Helicase enzyme unwinds the DNA and it unzips it in the area of the gene that needs to be copied

what is messenger RNA:

single-stranded molecule that carries genetic instructions from DNA to a cell's protein-making machinery. The cell copies a section of DNA to create an mRNA strand inside the protected nucleus.

What is the difference between RNA and DNA:

DNA = Data storage (stores genetic information)

RNA = Runner (carries instructions to make proteins)

In transcription what is the second step making mRNA:

an enzyme called RNA polymerase reads the DNA strand and creates A matching mRNA strand this mRNA strand is like a photocopy of the genes instructions which then allows the creation of specific proteins by the ribosomes.

In transcription what is the third step processing mRNA:

at the end of the gene a specific sequence of bases tells the RNA polymerase to stop copying as a result the mRNA molecule is released before the mRNA leaves the nucleus it gets a cap and a tail added for protection removing any unnecessary parts or introns.

In transcription what is the 4th step mRNA to ribosome:

the mRNA moves in the nucleus to the ribosome in the cytoplasm the ribosome is like a factory that makes proteins.

What are the four steps in translation:

reading mRNA, bringing amino acids, building the protein, finishing up

in translation what happened in the first step reading mRNA

the ribosome reads the mRNA in groups of three bases called codons each codon codes for a specific amino acid.

In translation what happens in the second step bringing amino acids:

transfer RNA molecules bring the correct amino acids to the ribosome as the ribosomes read the codons on the mRNA the tRNA with the complementary bases joined to the mRNA the sequence of three bases matching the codon is called the anticodon.

In translation what happens in the third step building the protein

the ribosomes the amino acids together in the correct order to form a protein chain

in translation what happens in the fourth step finishing up:

when the robber's arm reaches a stop codon on the mRNA the new protein is released and folds into its final shape to become functional.v

What is epigenetics:

the study of variations that occur due to the factors that switch genes on and off.

What is an epigenome:

it contains all the factors that influence the expression of genes other than DNA.

What are some examples of an epigenome:

stress, diet, toxins, exercise, sleep

what is chromatin:

to make DNA molecules fit in each cell they must be tightly coiled DNA coils around a specific protein called histones this DNA and histone network is called chromatin.

What are the two epigenetic factors that alter the shape of chromatin and the gene expression:

acetylation and methylation

what occurs in acetylation:

1. Acetyl group attaches to histone 2. Chromatin relaxes 3. Jane is now accessible to RNA polymerase for transcription (to be copied) 4. Gene expression is now enhanced

what occurs in methylation:

1. Methyl group attaches to CPG sites (cytosine-phosphorus-guanine: usually site on a DNA molecule or a cytosine nucleotide is next to a guanine nucleotide) 2. Methylation tightens the chromatin 3. RNA polymerase access to the gene is now restricted 4. Gene expression is stopped or prevented