(3.14-3.18B) DNA + protein synthesis

Define genome.

The entire DNA of an organism

Define gene.

A section of a DNA molecule that codes for a specific protein

What are chromosomes?

coiled up DNA double helix strands,

where genes are located

Where are chromosomes found?

In the nucleus of cells

What is DNA?

polynucleotide chemical that makes up the genetic material of organisms

What does DNA stand for?

deoxyribose nucleic acid

Describe the structure of DNA.

polymer made up on 2 strands coiled to form a double helix.

the strands are made of sugar phosphate backbones joined by complementary bases:

cytosine + guanine

thymine + adenine

What is RNA?

polynucleotide that plays a key role in protein synthesis

Describe the structure of RNA.

one polynucleotide strand made up of alternating ribose sugars and phosphate groups

with each base projecting out:

guanine + cytosine

uracil + adenine

What are the key differences between DNA and RNA?

RNA is:

single stranded

uracil instead of thymine

simpler

smaller

What is protein synthesis?

The process of turning a gene into the specific sequence of amino acids

that make up a specific protein

which is split into transcription + translation

What occurs during

1. transcription

2. translation-

   simply?

1. DNA is transcribed to produce an mRNA molecule

2. mRNA is translated to create an amino acid sequence

Where does transcription occur?

in the nucleus of a cell

Where does translation occur?

in the ribosome

Detail the process of transcription.

1. A protein is used to unwind a specific gene in a DNA molecule.

2. Exposes the template strand of bases that code for the protein.

3. Free mRNA nucleotides bind to complementary nucleotides in the strand with hydrogen bonds.

4. mRNA nucleotides joined to form a single stranded mRNA molecule

5. It leaves the nucleus via a pore in the nuclear envelope, travelling to the cytoplasm.

Detail the process of translation.

1. mRNA molecule attaches to ribosome- which reads the nucleotides.

2. cytoplasm has free tRNA molecules

   • triplet nucleotide bases- anticodon on one end

   • amino acid on the other

3. mRNA bases read in threes and tRNA anticodons pair with them complementarily- hydrogen bonds

4. codons continue binding, so amino acids continue binding, until ‘stop’ codon on mRNA molecule is reached

5. amino acid chain folds and modifies to form final protein molecule

6. RNAs become free nucleotides again as they can be reused.