Biology 1002B Study Guide - Dna Replication, Cell Theory, Cell Membrane
BIOLOGY 1202B EXAM 1
CELL STRUCTURE AND FUNCTION
THE THREE DOMAINS OF LIFE
1. Bacteria (Prokaryote) – 40 trillion cells
2. Archaea
3. Eukarya
THE CELL THEORY
1. All organisms are made of one or more cells
2. The cell is the basic unit of all living things
3. All cells come from existing cells
SYNTHETIC BIOLOGY
• Challenges cell theory #3
• DNA synthesized by a computer
• Craig Venture was the first to create the synthetic cell that can replicate
• Synthesize cells to fight diseases – cancer
• Synthesized cells to create imitation meat
• Much of the future will be synthetic biology
“BUILD YOUR OWN CELL”
PROKARYOTES VS EUKARYOTES
PROKARYOTES (Bacteria)
SHARED
EUKARYOTES
- Nuceloid
- Single circular chromosome
- Organelles absent
- Divide by binary fission
- Unicellular
- Typically, smaller
✓ Plasma membrane
✓ Cytoplasm
✓ DNA as genetic
material
✓ Ribosomes
- Nucleus
- Multiple linear
chromosomes
- Organelles present
- Divide by mitosis or meiosis
- Unicellular or multicellular
- Typically larger
WHICH OF THE FOLLOWING CAN BE FOUND INSIDE THE NUECLEUS OF EUKARYTOIC CELLS?
A. DNA
B. mRNA
C. Proteins
D. All of the above – proteins are in the nucleus, made in the ER and translated back into
the nucleus. E.g. histones, RNA polymerase, DNA polymerase, helicase
➢ RNA polymerase can be found in the cytoplasm where it is being made and being
ready to be imported into the nucleus
WHAT IS TRUE ABOUT THE MITOCHONDRIA
A. It contains circular DNA
B. Some of its DNA moved to the nucleus – small proportion of genes moved
C. It contains ribosomes – makes own proteins so needs ribosomes
D. All of the above –the mitochondria evolved from a prokaryotic cell (aerobic bacteria)
E. None of the above
THE THEORY OF ENDOSYMBIOSIS
➢ Ancestral prokaryotic cell engulfing either an aerobic cell or cyanobacteria or both
➢ Aerobic cell → mitochondria
➢ Cyanobacteria → chloroplasts
o Cyanobacteria performs oxidative photosynthesis
▪ The by product is the oxygen
▪ Advantage to aerobic cells → increase of high oxygen atmosphere
➢ Coexist in a symbiotic way – ancestral prokaryote needed something from the
membranes
EVIDENCE TO SUPPORT THE THEORY
1. Morphology
2. Reproduction – binary fission
3. Genetic information – prokaryotic DNA
4. Transcription and Translation – independent of the nucleus
5. Electron Transport
6. Sequence Analysis
WHY ARE EUKARYOTIC CELLS ABLE TO GROW LARGER THAN PROKARYOTIC CELLS?
➢ The plasma membrane limited by surface area and need to increase surface area by
engulfing eukaryotes
WHY DO CELLS GROW TO A LIMITED SIZE AND THEN HAVE TO DIVIDE?
➢ The volume of a cell grows much faster than the surface area
➢ Needs to maintain surface area to volume ratio to survive
Surface Area to Volume Ratio (SA:V)
Surface Area = 4𝒓𝟐
Volume = 4/3𝒓𝟑
1. Surface area to volume ratio is important in the limitation of cell size.
• To survive, cells need to produce energy (metabolism) which requires the exchange
of materials with the environment via the plasma membrane
o Nutrients enter through surface area
• Larger cells need more energy to sustain essential function
• Large membrane surface equates to more material movement
• When a cell gets too big, the small surface area doesn’t allow enough nutrients to
enter the cell quickly enough for the cell’s needs
• Growing cells need to divide in order to maintain a high surface area to volume ratio
suitable for survival
DOES EUKARYOTIC CELL HAVE A HIGHER OR LOWER SA:V RATIO TO PROKARYOTIC CELL?
➢ Prokaryotic cells
CELL SIZE AND SHAPE VARITATIONS IN HUMANS
• As efficient as possible in the shape they are in