BIOLOGY MIDTERM (WINTER 2010) (PART 1) - BIOLOGY MIDTERM...

BIOLOGY MIDTERM- WINTER 2010 AASEFA SHAIKH
Chapter 2 and 13-
= answer to learning objectives
CELLS AND CELL THEORY (PART ONE)
Two major unifying concepts of biology
Theory of Evolution by natural selection Cell Theory
• traits change over time (pattern)
• ppl with certain heritable traits have more offspring
then others w/out the traits (mechanism)
• All spp. are related by descent from a common
ancestor and all spp. descend from other pre-
existing spp.
• all organism made up of cells (pattern)
• all cells come from pre-existing cells
(mechanism)
• all single cell organisms in 1 population are
related to 1 common ancestor and all cells in a
multi-cellular organism descend from 1 ancestral
cell
Cells- Organisms
Single celled Multi-cellular
- Bacteria
- Archaea
- Amoeba
- Paramecia
- Some algae
- Yeast(some type of fungi)
- Plants
- Animals
- Some algae
- Some fungi
- All cells have:
1. Ribosomes  protein production
2. Plasma membrane
3. Chromosomes
- Mitochondria
 “power house” - makes ATP
 E. Coli- prokaryotes don’t have mitochondria bc its too big to fit into the cell
The information system of the cell
DNA  RNA  PROTEIN
1. Info stored in DNA
2. Info in DNA copied into RNA
3. Info in RNA guides production of protein
- All cells share an info system
- Blue-print/ long-term storage in DNA
- RNA  makes proteins
e.g.:
- DNA= grandma’s cookbook
- Genes= recipes
- Transcription= transferring recipe onto recipe card
- Recipe card= messenger (mRNA)
Sequence for a gene is copied form
DNA to an mRNA
- Some cells are
organisms while other
organisms are made up
of many cells

- Translation = turning words into physical item
Deoxyribonucleic acid (DNA)
- Series of 5 deoxy-ribose sugar that is connected to nitrogenous bases and a phosphate group
- A, C

purines (2 rings)
T, G

pyridines
- Complimentary base pairing
A-T
C-G
- If you have 2 pyrines or 2 pyridines then
- DNA has a direction- you read it in a particular way (paired in opposite direction 5’ - 3’)
- In RNA

no T, there is U (uracil) which is a ribose sugar
Proteins being made by each ribosome
- Different types of RNA
1. mRNA- messenger RNA
 gene transcript
 made by transcription
2. tRNA- transfer RNA
 used in making proteins in transition
 bring amino acids to the ribosome
3. rRNA- ribosomal RNA
 found in ribosomes (w/ ribosomal proteins)
** To make proteins you need all the types of RNA
Transcription and translation
- prokaryotes (e.g. bacteria, archaea)
 no nucleus
 transcription and translation can occur at the same time
 prokaryotes can begin translation even as mRNA is being transcribed
 prokaryotes are 10 folds smaller than eukaryotes but DNA and ribosomes are of similar size
- eukaryotes
 nucleus present
 translation occurs after transcription has finished (both don’t occur at the same time)
 eukaryotes can begin translation only after mRNA is exported from the nucleus
 transcription and translation is similar in plants, animals, and fungi
Sequence for a gene, now encoded in
mRNA, is used to direct the production
of a protein

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