RNA + DNA - chapter 15

DNA stands for

deoxyribonucleic acid

RNA stands for

ribonucleic acid

heredity

passing on of features from parents to offspring

gene

a section of DNA that causes the production of proteins (units of heredity)

gene expression

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

characteristics

traits that are inherited genetically

chromosomes

60% protein, 40% DNA, non-coding DNA are arranged along the DNA of a chromosome in a line, large sections of the chromosomes are not made of working genes

non-coding DNA

doesnt cause the production of a protein(sugar-phosphate)

nucleotides

are carbon ring structures containing nitrogen linked to a 5 carbon sugar, made of nitrogeneous base

complementary pair

each base has a different matching base, A+T-2 hydrogen bonds, C+G-3 hydrogen bonds

purines

A-adenine, G-guanine, (double ringed)

pryimidines

T-thymine (U-uracil is RNA), C-cytosine

DNA structure

2 attached strands, held by commentary bonds, it twisted to form a spiral structure a double helix

double helix

phosphate on the outside then sugars and bases on the inside, discovered by James Watson + Francis Crick

the genetic code

the sequence of bases in DNA that provide the instruction for a cell using RNA to form a protein, a gene is expressed when this code is sent to the cytoplasm to form a protein, many triplets form a sequence

proteins

made of combinations of thousands of amino acids (20 types) joined together, gene carries a different code to control the assembly of each aminoacid

triplet/codon

is a sequence of three bases in DNA/RNA that act as a code for an amino acid

DNA replication

double helix unzips/uncoils. enzymes break hydrogen bonds, complementary strands move apart. DNA nucleotides from cytoplasm attach to complementary bases on exposed strands. each side of DNA molecule acts as a mould for a new DNA is formed. each new double strand rewinds to form a double helix, the new DNA strand is identical to the original.

DNA profiling

is a method of making unique pattern of bonds form the DNA of a person. used in forensic science-crime scenes, establish paternity

DNA profiling process

DNA is isolated and released from cells as they are broken down, if amount of DNA is too small it can be increased-polyrnerase chain reaction. DNA strands are cut into fragments using restriction enzymes. fragments are separated based on their length - they are placed in gel and an electric current is passed through - gelelectrophoresis. the pattern is then anaylsed and compared.

genetic screening

testing DNA for presence or absence of genes, radioactive section of DNA is added to a sample of DNA from a person; the probe will not attach to an altered gene

adult screening

genetic disorders caused by defective genes; albinism the pigment melanin cannot be made, cystic fibrosis build up of mucus on lungs and intestines, haemochromatosis too much iron, cancer

embryonic/foetal screening

cells can be removed from the embryo, placenta or fluid, the cells can be tested if foetus/embryo has one of the genetic disorders

protein synthesis process

the sequences of bases on a DNA strand carries instructions to make a certain protein. the bases in DNA and RNA work in groups of three bases causes one particular amino acid to become part of the protein. the DNA strands separate, happens in nucleus. RNA bases attach to the exposed baseson one side of the DNA. this means that the code has been transcribed from DNA to complementary strand of RNA(mRNA). the mRNA strand detaches from the DNA and moves into the cytoplasm. the mRNA passed through a ribosome, amino acids attach to the protein in ribosome. the code on the mRNA is translated into the correct sequence. the protein becomes folded as it emerges from the ribosome, allows protein to carry out function.

protein synthesis in eukaryotic

DNA - > transcription - > RNA - > translation - > protein

protein synthesis in prokaryotic

DNA - > RNA - > protein

transcription

the transfer of information in the nucleus from DNA to RNA. one DNA strand acts as a template. takes place in nucleus. DNA uncoils. the exposed DNA bases are matched up with RNA bases in the nucleus to form mRNA due to polymerase

mRNA

happens in nucleus, carries the information for a specific protein, 500-1000 nucleotides long, made of codons.

tRNA

picks up appropriate amino acids to the mRNA + translates mRNA into strand of amino acids, has anticodons that are complimentary to mRNA with H-bonds.

rRNA

structural component of ribosome associated with proteins

ribosomes

large or small subunits, composed of rRNA and proteins, units bind mRNA and tRNA

translation

cytoplasm, mRNA binds to a ribosome, the strand of mRNA is pulled through ribosome three bases, a ribosome on rough endoplasmic reticulum attaches to the mRNA molecule, a tRNA brings an amino acid to first colon on the mRNA (leaves chain), another tRNA brings an amino acid anticodon links up with second codon, a third tRNA brings another amino acid to form a polypeptide chain, the process continues until a termination is reached, requires enzymes and ATP (AdenineTriPhosphate)

end product

is a primary structure of a protein, a sequence of amino acids bonded together by peptide bonds

functional protein

protein undergoes folding and the addition of bonds, folding allows the protein to reach its 3D (tertiary shape) which influences its function