Biology Chapter 7: DNA Structure and Gene Function

DNA

Deoxyribonucleic Acid a molecule with a remarkable function: It stores the information that each cell needs to produce proteins.

Nucleotides

Form DNA's building blocks, and they knew that each nucleotide included one type of base Adenine, Cytosine, Guanine, Thymine.

The two strands of a DNA molecule are...

Complementary to each other.

Genome

All of an organisms genetic material in its cells.

Chromosome

A discrete package of DNA coiled around proteins.

Gene

A sequence of DNA nucleotides that encodes a specific protein or RNA molecule the human genome includes 20,000 to 25,000 genes scattered on its 23 pairs of chromosomes.

Transcription

A cell rewrites a gene's DNA sequence to complementary RNA molecule.

Translation

The information in RNA is used to assemble a different class of molecule: protein

Messenger RNA

Carries the information that specifies a protein the mRNA is divided into genetic "code words" called codons.

Codon

A group of three consecutive MRNA bases that corresponds to one amino acid.

Transfer RNA

Molecules are "connectors" that bind an mRNA codon at one end and a specific amino acid at the other.

Ribosomal RNA

Combines with proteins to form a ribosome.

Ribosome

The physical location where translation occurs.

Template Strand

Contains the DNA sequence that is actually copied to RNA

RNA Polymerase

The enzyme that builds an RNA chain, may then attach to the promoter.

Genetic Code

The set of "rules" by which a cell uses the codon in mRNA to assemble amino acids into a protein.

Anticodon

A three-based loop on a TRNA that is complementary to one mRNA codon.

Chromosomes

discrete packages of DNA coiled around proteins.

RNA

nucleic acid that participates in protein synthesis

three RNAs interact with each other to synthesize proteins during translation.

gene

• is a small region of a chromosome.

• The sequence of DNA in each gene encodes a specific protein.

The nucleotide sequence of mRNA depends

directly on DNA’s nucleotide sequence.

The amino acid sequence in protein is dictated

the nucleotides in the mRNA molecule.

covalent bonds

join together nucleotides into chains called DNA “strands.”

Each DNA molecule is made up of

two strands of nucleotides. The two strands wind together into a “double helix” shape.

• DNA strands are

• antiparallel to each other and complementary to each other

• The three parts of a nucleotide are a

• phosphate group, a five-carbon sugar, and a nitrogenous base.

• DNA is nucleic acid composed of

• nucleotides

• All cells use DNA to store genetic information, which is what cells need to

• produce proteins.

Proteins

Chains of amino acids that fold into incirrate( 3 dimensional shape).

DNA (deoxyribonucleic acid)

genetic material consisting of a double helix of nucleotides, each containing the sugar deoxyribose.

*Stores the information in each cell needed to produce proteins.

*Before a cell divides, it first makes a replica of its DNA. it copies all the information to enable the next generation of cells to live.

Enzymes

Proteins interact with this chemical inside a cell to speed up chemical reactions

-Breaks down food builds the cell structure, places blood type on red blood cells surface, produces melanin pigment in your skin, color of your eyes etc.

James Watson and Francis Crick

used two lines of evidence to deduce DNA’s structure.

-1940s deduced that each gene somehow controls the production of one protein.

.Biochemist Erwin Chargaff 

-

-show the amount of guanine in a DNA molecule always = the amount of cytosine 

-the amount of adenine always = the amount of thymine.

2.English Physicist Maurice Wilkins and Chemist Rosland Franklin

-used a technique called X-Ray diffraction to reveal a repeating structure of building blocks, consistent with a helix.

Adenine and guanine bases

double ring structure

Cytosine and Thymine

each has a single ring

DNA has

sugar of H, AG CT(thymine) BASES, double-stranded, and stores RNA to transfer info to the next cell.

RNA has

sugar of OH, AG CU(uracil) bases, single-stranded, and carries protein encoding info, helps to make proteins and catalyzes some reactions,

DNA pairs with

RNA

RNA pairs with

RNA

Codon

a triplet of mRNA bases that specifies a particular amino acid or a “stop” signal