Biology - DNA and RNA

Heredity

the passing on of features from parents to offspring by means of genes

Gene

a section of DNA that causes the production of a protein

Gene Expression

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

Characteristics

traits or features that are inherited genetically

Deoxyribonucleic Acid

DNA

Non Coding DNA

aka junk DNA

DNA that does not cause the production of a protein

Bases in DNA

• adenine (A)

• thymine (T)

• guanine (G)

• cytosine (C)

Hydrogen Bonding

links the base pairs in the DNA molecule

Structure of DNA

• strands of DNA held together by complementary bases

• double-stranded

• double helix shape

Chromosomes

are made of DNA and protein

Genetic Code

the sequence of bases in DNA that provide the instruction for a cell (using RNA) to form a protein

20

number of different types of amino acids used in proteins

Codon

aka triplet

a sequence of three bases in DNA (or RNA) that acts as a code for an amino acid

DNA Replication

• the double helix unwinds

• new DNA strands are made

DNA Profile

a method of making a unique pattern of bands from the DNA of a person, which can then be used to compare with the DNA profile of another person

Preparing a DNA Profile

1. DNA is released from cells

2. DNA is cut into fragments of different lengths

3. DNA fragments are separated according to their sizes

4. Pattern is analysed

Forensic Medicine

the way in which medical knowledge is used in legal situations

Genetic Screening

testing DNA for the presence or absence of a particular gene or an altered gene

Ribonucleic Acid

RNA

RNA

• has the sugar ribose

• contains the base uracil (U)

• single-stranded

• found in the nucleus and cytoplasm

DNA

• has the sugar deoxyribose

• contains the base thymine (T)

• double-stranded (double helix)

• found in the nucleus (can also be found in mitochondria and chloroplasts)

Transcription

the copying of a sequence of genetic bases from DNA onto messenger RNA (mRNA)

Translation

the conversion of a sequence of genetic bases on messenger RNA into a sequence of amino acids

Nucleotide

consists of three parts : a phosphate group, a sugar(deoxyribose or ribose) and a nitrogenous base

Purine Bases

adenine (A) and guanine (G)

Pyrimidine Bases

thymine (T) and cytosine (C)

Francis Crick and James Watson

discovered that DNA consisted of two helical or spiral chains of polynucleotides

Protein Synthesis

• enzymes open up the DNA at the site of a gene

• DNA code is transcribed onto a complementary RNA strand

• mRNA enters a ribosome in the cytoplasm

• tRNA has a complementary codon to the codons on the mRNA

• tRNA enters the ribosome

• tRNA has a specific amino acid

• amino acids are attached to each other at the ribosome to form protein

• protein folds into shape

Anticodon

a sequence of three bases on tRNA that are complementary to a sequence of three bases on mRNA

mRNA

(messenger RNA)

• complementary strand to DNA

• carries instructions for the production of a protein from DNA to a ribosome

tRNA

(transfer RNA)

• has a complementary anticodon to mRNA codon

• carries an amino acid to the ribosome

rRNA

(ribosomal RNA)

• forms part of the structure of a ribosome

• forms a weak bond with mRNA in the ribosome