DNA - Semester 2

What is the structure of DNA?

double helix (twisted ladder). Composed of deoxyribose sugars, phosphate groups, and nitrogenous bases.

What are the directions of the two anti-parallel strands of DNA?

Goes from 5' to 3' and from 3' to 5'

What are the 5 nitrogenous bases?

Adenine, Thymine, Cytosine, Guanine, Uracil

What is Chargaff's base pairing rule?

A=T and C=G and for RNA its A=U

What are the 3 bacterial shapes?

Coccus (spherical), bacillus (rods), spirochetes (spirals)

What are the two cell wall structures?

Gram-positive: purple color

Gram-negative: pink color

How does DNA store information?

DNA stores information as a sequence of nucleotide bases (ATCG)

What are nucleotides?

building blocks of DNA

How did Franklin use X-rays?

He used a method called X-ray diffraction to study the structure of DNA.

What did Watson and Crick do?

The data from Franklin's X-rays helped Watson and Crick explain the structure and its properties.

What does DNA polymerase do?

Synthesizes new DNA strands by adding and proofreading nucleotides during replication.

What does ligase do?

joins fragments together from the lagging strand, ensuring a complete strand

What are genes?

Genes are sections of DNA that control a single genetic trait.

What is complementary base pairing?

When base A always pairs up with base T, and base C always pairs up with base G

What is the backbone of DNA?

phosphate -> sugar -> phosphate -> sugar

How are nucleotides joined together to form DNA?

covalent bonds

What happens during DNA replication?

The DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template, or model, for the new strand

What does helicase do in DNA replication?

Unwinds DNA by breaking hydrogen bonds

In RNA, what nitrogenous base is different?

Uracil instead of thymine

Instead of deoxyribose, RNA contains

ribose

How many strands does RNA have?

1 strand

DNA is in the nucleus, and RNA is in

Cytoplasm, but made in the nucleus

Why can't DNA leave the nucleus?

It's too big

What are the three types of RNA?

Messenger RNA (mRNA)

Transfer RNA (tRNA)

Ribosomal RNA (rRNA)

What happens in transcription?

DNA turns into mRNA.

What binds to the promoter in transcription?

RNA polymerase

What is a codon?

a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule

What are introns and exons?

Introns are junk DNA- noncoding sequences. Exons are functional mRNA coding regions

What pieces of DNA are left out and kept in?

Introns are cut out and exons are left in

In strands of DNA, the lower-case letters are

Introns so they should be left out. Only translate the uppercase letters.

What is the start codon for translation?

AUG (methionine). Draw the first box around this then continue in pairs of three.

What does tRNA do?

Carries amino acids to ribosomes

What does mRNA do?

messenger, contains the information from DNA to make proteins by translation

What does transcription do?

Turns DNA into RNA

What does translation do?

RNA to protein

Where does translation occur?

Cytoplasm

Where does the mRNA attach to?

rRNA (Ribosome)

What happens in translation?

The ribosome reads the mRNA and turns it into protein. the tRNA has an anti-codon which matches with pair codon on the mRNA which releases the amino acid on the tRNA to make a protein. The rRNA makes sure everything is aligned and releases the protein once it is finished

What is the stop codon?

UGA

What is protein folding?

The physical process by which a polypeptide folds into its functional form, so it can actually work

What are ionic interactions in proteins?

Attractions between positively and negatively charged atoms that stabilize protein structure

What are hydrogen bond interactions in proteins?

They are weak attractions between slightly charged atoms (O or N) that help stabilze secondary and tertiary structure of proteins

What are disulfide bond interactions in proteins?

Covalent bonds are formed between sulfur atoms of cysteine side chains that stabilize tertiary and quaternary structure of proteins

What are hydrophobic interactions in proteins?

Hydrophobic interactions are the tendency of nonpolar amino acid side chains to associate together in the interior of proteins to avoid contact with water.

What does the zone of inhibition indicate?

It indicates the bacteria killed by the antibiotic. The larger the zone the more effective the antibiotic.

If an antibiotic has very little or no zone of inhibition, the bacteria is likely resistant to the antibiotic.

What is the difference between gram + and gram - bacteria?

Gram + has a thick peptidoglycan layer while gram - has a thin layer. Gram - also has an outer membrane while + doesn't.

What does the promoter do?

site where RNA polymerase binds to begin transcription

What is the difference in structure between deoxyribose and ribose?

Ribose has one less oxygen molecule than deoxyribose

What happens at the APE sites of rRNA?

tRNA enters at the A site, the growing chain at the P site is transferred to the A site and the new tRNA moves to the P site with the growing chain and the empty tRNA leaves out the E site. The first tRNA carrying met binds at the P site while the others at the A site.