LC Biology- DNA + RNA

heredity

passing on features from parents to offspring by means of genes

gene

a length of DNA that codes for a specific protein

gene expression

the way in which the genetic information is decoded in the cell and used to make a protein

example of gene expression

gene for tallness, lack of nutrition not reaching potential height

structure of a chromosome

40% DNA and 60% Protein

non-coding DNA

long sections of the chromosomes that do not contain genes

4 bases that make up DNA

adenine, thymine,guamine, cytosine

nucleotide

a basic building block of RNA or DNA containing a nitrogenous base, a sugar molecule and a phosphate group

Similarities of DNA and RNA

• both nucleic acids

• both contain a,g and c nucleotides

• operate together to produce specific proteins

Differences of DNA and RNA

DNA

-double stranded

-sugar is deoxyribose

-has thymine

-self replicating

-found only in nucleus

RNA

-single strand

-sugar is ribose

-has uracil

-short molecule

-not self replicating

-found in nucleus cytoplasm

RNA

ribonucleic acid, operates with DNA to make protein

Complimentary base pairs:

• Adenine --------->Thymine

• Guanine ---------> Cytosine

DNA replication

1. Double helix unwinds

2. Enzyme breaks bond between base pairs, separating the 2 strands

3. Bases move into nucleus from the cytoplasm and attach to exposed complimentary base pairs

4. Each DNA molecule acts as a template from the newly formed DNA

5. Each new double strand rewinds to form a double helix again

DNA Profile

• Profiles are obtained by

1. Releasing DNA from cells

2. Cutting DNA into fragments using restriction enzymes (restriction enzymes cut at specific base sequences)

3. Separating fragments according to size (process called gel electrophoresis) 4. Fragment patterns are analyzed

Protein synthesis

• The way in which DNA produce protein

1. Base sequence on DNA strand act as a code to carry instructions for a certain protein

2. Base on the DNA link with complimentary bases on mRNA (messenger RNA) – transcription occurs

3. mRNa detaches from DNA, moves out of nucleus and enters a ribosome

4. Correct sequence of amino acids is linked together in the ribosome to form a protein (code is translated)

5. Protein becomes folded as it leaves the ribosome

Transcription

copying of a sequence of genetic bases from DNA to mRNA

Translation

conversion of a genetic sequence of bases on mRNA into a sequence of amino acids.

Detailed structure of DNA (Higher Level)

• DNA consists of nucleotides

• Nucleotides consist of 3 parts

• A phosphate, deoxyribose sugar & base

Protein synthesis

1. Initiation

• DNA double helix unwinds at site of gene that will produce the protein

• Unwinding carried out by enzymes

2. Transcription – rewriting code from DNA -> RNA

• DNA code is transcribed onto a complimentary mRNA strand

• A sequence of 3 bases is called a codon

• Start codon indicates the beginning of a gene

• Stop codon indicates the end of gene

3.Translation

• mRNA enters a ribosome

• Each tRNA has a complementary triplet (anti-codon) that links to the codon on the mRNA

• tRNA enters the ribosome, each tRNA has a specific amino acid

name the component of a nucleotide that is neither a carbohydrate of nitrogenous base

phosphate

what does the “m” stand for in mRNA?

messenger RNA

to isolate DNA from plant tissue: why is salt used

DNA clumps together

to isolate DNA from plant tissue: why was washing up liquid used?

to break down cell membrane

to isolate DNA from plant tissue: why was the beaker put in an ice bath for 5 minutes?

to prevent the DNA from being broken down

to isolate DNA from plant tissue: why was the mixture filtered

to remove debree

to isolate DNA from plant tissue: why was protease added to the mixture

to break down protein

stretch of DNA strand with base sequence: ATTGGCATT what would the complimentary DNA strand be?

TAACCGTAA

during protein synthesis the ribosome translates the codon on mRNA with the help of:

restriction enzymes