Intro to Cells - Chapter 4 + 5

DNA (what does it stand for)

deoxyribonucleic acid

RNA (what does it stand for)

ribonucleic acid

DNA & RNA function:

Polymers: Store, transmit, and use genetic information

Central Dogma

1) DNA copies itself

2) Transcription (nucleotides form base pairs with other nucleotides)

3) RNA forms (taking specific sections of DNA copy needed for proteins)

4) Translation (nucleotides —> Amino Acids, through a ribosome)

Nucleotides Structure

1) Pentose (monosaccharide with 5 Carbons)

2) Phosphate group

3) Nitrogen containing base

Pentose Names

DNA: deoxyribose (No oxygen)

RNA: ribose

Nucleotides

Adenine (two rings)

Thymine

Cytosine

Guanine (two rings)

Uracil

All held together by hydrogen bonds

Complimentary base pairs

Adenine — Thymine (Double hydrogen bond)

Cytosine — Guanine (Triple hydrogen bond)

In RNA: Adenine — Uracil (Double hydrogen bond)

RNA

1) Single stranded

2) Intermediate between genetic information encoded in DNA which specify the sequence of Aa needed to make a protein.

3) RNA uses this information to add amino acids in the right order when making proteins.

4) Uracil replaces Thymine

5) RNA has lots of folds and loops because of base pairs

6) Original genetic material was RNA; not DNA

DNA

1) Double stranded (helix)

2) Strands connected to one another through base pairs

3) two strings of nulceotides

4) run in opposite directions (anti-parallel)

5) In charge of coding genetic information

6) Info coded in the SEQUENCE of the nucleotides

7) Base pairs connected by HYDROGEN bonds

DNA replication

1) 2 complete copies of the DNA molecule are made

2) Only the DNA sequences that encode specific proteins are transcribed into RNA

Evolutionary relationships

DNA base sequences reveal evolutionary relationships

Other role for nucleotides

1) ATP (energy)

Ribozymes

1) RNA molecule that acts like an enzyme

2) stores information, transmits information, cuts up and put things together.

Original Central Dogma

RNA replicated itself and made proteins. Protein and DNA evolved and did their seperate tasks, rely on RNA to intermediate.

Why are cells extremely small?

1) Cells have to exchange molecules with the environment (taking things in, excreting, etc.)

2) Volume of Cell —> how much chemical activity occurs in the cell

3) Surface area —> exchange with environment

4) Ratio between SA and V gets smaller as volume increases. Better to have small cells because lots of SA compared to V, more interactions with the environment.

What do all cells share?

1) Plasma membrane

• maintain constant environment

• selectively permeable

• communicate with environment

2) Genetic Material

• Ex: DNA —> RNA —> Protein

• Ribosome in charge of translation

Two kinds of cells

1) Prokaryotic

• No nucleus

• DNA in nucleoid

• Smaller than Eukaryotic cells

• enclosed by plasma membrane

• very diverse; where live & energy source

2) Eukaryotic

• have smaller compartments within the cell

• Nucleus is biggest compartment (holds DNA)