DNA Science

Biology I Factoids

Factoid 154

• Section 10

• DNA controls the production of every protein in a cell. Proteins control all of the process in a cell.

Factoid 153

• DNA is made up of nucleotides. Nucleotides are made up of a sugar (either ribose for RNA or deoxiribose for DNA), a phosphate group, and a nitrogen base.

Factoid 154

• There are 5 nitrogen bases:

• Adenine and Guanine are purines.

• Cytosine, Thymine, and Uracil are Pyrimidines.

• Uracil is only found in RNA not DNA.

Factoid 155

• In 1953 two scientists named James Watson and Francis Crick were the first people to determine the structure of DNA

Factoid 156

– DNA is like a twisted ladder (called a double helix) whereby the sugar and phosphate units make up the sides of the ladder and the nitrogen bases make up the steps of the ladder.

Factoid 157

• The sequence of the nucleotides in DNA determines the information that is passed on by the genes.

Factoid 158

• DNA replication (during the S phase of the cell cycle) makes a copy of the DNA. The DNA ladder splits and nucleotides join to form an extra copy of DNA.

Factoid 159

• Since DNA will contain one old strand and one new strand of DNA, the process is called semi-conservative.

Factoid 160

• There are 3 ways DNA and RNA are different:– RNA has a ribose sugar unit instead of the

deoxiribose sugar unit.– DNA is double stranded and RNA is single

stranded.– In RNA A pairs with U and not T. There is no

Thymine in RNA.

Factoid 161

• There are 3 types of RNA– Messenger RNA (mRNA) carries instruction

from the DNA to the ribosomes.

Factoid 162

– Transfer RNA (tRNA) bring amino acids to the ribosomes.

Factoid 163

– Ribosomal RNA (rRNA) bind with the ribosomes to help make proteins.

Factoid 165

• Protein synthesis (the making of proteins) has two parts: Transcription and translation.

Factoid 165

• To transcribe DNA means to make a copy of it. When DNA is transcribed, a copy of the nucleotide sequence is copied by RNA.

Factoid 166

• Transcription makes mRNA in the nucleus. The mRNA then leaves the nucleus.

Factoid 167

• Nucleotides are “read” in groups of 3 (called a codon). Every 3 nucleotides code for 1 amino acid.

Factoid 168

• During translation, the mRNA is bound to an rRNA and a ribosome. The ribosome makes the new protein.

Factoid 169

• The tRNA brings an amino acid to the ribosome to build the protein.

Factoid 170

• Chargaff’s Rules

• A always bonds with T and visa versa

• C always bonds with G and visa versa

• In RNA, A always bonds with U and visa versa.

Factoid 171

• The process of protein synthesis can be summarized:

DNA mRNA ribosomes protein

Factoid 172

• The study of DNA molecules and making changes in DNA is called molecular genetics.

Factoid 173

• A subfield of molecular genetics is called genetic engineering which involves changing an organism’s DNA

Factoid 174

• The first step in examining an organisms DNA is DNA extraction or removing the DNA from the cell.

Factoid 175

• DNA is very large. It must be cut into smaller pieces using restriction enzymes.

Factoid 176

• Restriction enzymes cut DNA in very specific sequences. They will only work on a specific nucleotide sequence.

Factoid 177

– Once cut into pieces (called fragments) the DNA is separated using gel electrophoresis.

Factoid 178

• DNA travels from the negative side of the DNA gel to the positive side of the gel. The smaller fragments travel farther and make a banding pattern on the gel.

Factoid 179

• Patterns on a DNA gel can be used to prove or disprove paternity, guilt or innocence of a crime, determining evolutionary history, etc

Factoid 180

• Taking short pieces of DNA from one organism and joining it to the DNA of another organism is called recombinant DNA.

Factoid 181

• Transgenic organisms are organisms that contain genes from a different organism.

Factoid 182

• Cloning refers to taking genetic information out of a donor cell and placing it into an egg, then implanting the egg in a female for birth.

Factoid 183

• Mutations are mistakes in DNA that can be beneficial, harmful, or have no effect at all.

Factoid 184

• There are two types of mutations gene mutations (or point mutations) or chromosome mutations.

Factoid 185

• There are three types of gene mutations• Insertion – A nucleotide is added and changes the

codons.• Substitution – A different nucleotide is inserted

instead of the intended one.• Deletion – A nucleotide is left out.

Factoid 186

• There are 4 types of chromosome mutations

• Deletion – A piece of chromosome is removed.• Duplication – Part of a chromosome is copied• Inversion – Pieces of chromosomes switch places.• Translocation – Pieces of one chromosome

change places with pieces from another chromosome.

Factoid 187

• Karyotype – A picture of chromosomes used to see if there are abnormal numbers of chromosomes