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Cell Theory
• Every organism is composed of one
or more cells
• Cell is smallest unit with properties of
life
• Continuity of life arises from growth
and division of single cells
• Smallest unit of life
• Is highly organized for metabolism
• Senses and responds to environment
• Has potential to reproduce
Cell
The cell theory states that _____.
1 2 3 4
0% 0%0%0%
1. every organism consists of one or more cells
2. the cell is the smallest unit of organization that displays all the properties of life
3. the continuity of life arises directly from the growth and division of single cells
4. all of the choices
Structure of Cells
All start out life with:– Plasma membrane – Region where DNA
is stored– Cytoplasm
Two types:– Prokaryotic– Eukaryotic
DNA innucleoid
cytoplasm
plasma membrane
Bacterial cell (prokaryotic)
Fig. 3-1a, p.39
Types of Cells
The DNA of a prokaryotic cell is located in the _____.
1 2 3 4
0% 0%0%0%
1. nucleus2. plasma
membrane3. nucleoid4. cell wall
DNA in nucleus
cytoplasm
plasma membrane
Plant cell (eukaryotic)
Fig. 3-1b, p.39
Types of Cells
Fig. 3-4, p.41
Most Cells Are Really Small
• Create detailed images of something that is too small to see
• Light microscopes– Simple or compound
• Electron microscopes– Transmission EM or Scanning EM
Microscopes
Limitations of Light Microscopy
• Cells must be thin enough for light to pass through
• Structures are usually stained
• Light microscopes can see details 200 nm in size
Fig. 3-2a, p.40
Microscopes
Ocular lens enlargesprimary image formedby objective lenses.
Path of light rays(bottom to top) to eye
Prism (directs rays to
ocular lens)
Objective lenses (closestto specimen) form primary image.
Stage (holds microscope slide in position)
Condenser lenses focus light rays through specimen.
Illuminator
Fig. 3-2a, p.40
Electron Microscopy
• Uses beams of electrons rather than light
• Electrons are focused by magnets rather than glass lenses
• Can resolve structures down to 0.5 nm
Different Views
Structure of Cell Membranes
• Fluid mosaic model
• Mixed composition:– Phospholipid bilayer – Glycolipids– Sterols– Proteins
• Archaebacteria and eubacteria
• DNA is not enclosed in nucleus
• Generally the smallest, simplest cells
Prokaryotic Cells
Fig. 3-8b, p.44
The DNA of a typical prokaryote is organized into _____.
1 2 3 4
0% 0%0%0%
1. a single circular chromosome
2. many rod-shaped chromosomes
3. a corkscrew shaped chromosome
4. a spherical jellylike mass in the nucleoid region
Eukaryotic Cells
• Have a nucleus and other organelles
• Eukaryotic organisms– Plants– Animals– Protistans– Fungi
Eukaryotic Cell Features
• Plasma membrane• Nucleus• Endoplasmic
reticulum• Golgi body• Vesicles• Mitochondria• Ribosomes• Cytoskeleton
Fig. 3-9b-c, p.46
ribosome vesicle
rough ER
The Nucleus
Endoplasmic Reticulum
• Starts at nuclear membrane and
extends throughout cytoplasm
• Rough ER: ribosome covered,
processes proteins
• Smooth ER: no ribosomes, builds lipids
Fig. 3-9e-f, p.46
budding vesicle
Golgi body
plasma membrane
Secretory pathway ends.
Endocytic pathway begins.
Golgi Body
Vesicles
• Membranous sacs that
move through cytoplasm
• Lysosomes
• Peroxisomes
Cogito ergo….
sum
non s
um
0%0%
1. sum
2. non sum
• ATP-producing powerhouses
• Membranes form two distinct
compartments
• ATP-making machinery embedded
in inner mitochondrial membrane
Mitochondria
Fig. 3-10, p.48
outer membrane
outer compartment
inner compartment
inner membrane
FOOD
complex carbohydrates
simple sugars
pyruvate
acetyl-CoA
glycogenfats proteins
amino acids
carbon backbones
fatty acids
glycerol
NH3
PGAL
glucose-6-phosphate
GLYCOLYSIS
KREBS CYCLE
urea
Krebs cycle
Fig. 3-9a, p.46
chromatin
nucleolus
nuclear envelope(two lipid bilayers)
The Nucleus
Figure 6.5Page 87
2 ATP
4 ATP
glucose
2 PGAL
2 pyruvate
2 ATP
2 acetyl-CoA
36 ATP
ATP
ATP
Krebscycle
NAD+
2 NADH
2 NADH2
2 FADH2
6 NADH
2 NADH
2 CO2
4 CO2
ADP+Pi
electrontransfer
phosphorylation
H+
H+
H+
H+
H+
H+
H+
H+
H+
The function of a mitochondrion is to _____.
1 2 3 4
0% 0%0%0%
1. produce protein
2. make ATP3. attach sugar
side chains to some proteins and lipids
4. degrade toxins
Chloroplasts
• Convert sunlight energy to ATP through photosynthesis
• Found in plants and some protistans
Fig. 3-11, p.48
two outermembranes
thylakoids(inner membranesystem folded intoflattened disks)
Griffith Discovers Transformation
• 1928
• Attempting to develop a vaccine
• Isolated two strains of Streptococcus pneumoniae– Rough strain was harmless– Smooth strain was pathogenic
Griffith Discovers Transformation
1. Mice injected with live cells of harmless strain R
2. Mice injected with live cells of killer strain S
3. Mice injected with heat-killed S cells
4. Mice injected with live R cells plus heat-killed S cells
Mice die. Live S cells in their blood
Mice live. No live R cells in their blood
Mice die. Live S cells in their blood
Mice live. No live S cells in their blood
Transformation
• Harmless R cells were transformed by material from dead S cells
• Descendents of transformed cells were also pathogenic
What Is the Transforming Material?
• Avery found protein-digesting enzymes did not change results– extracts still transformed bacteria
• But treated with DNA-digesting enzymes– extracts lost transforming ability
• Concluded that DNA, not protein, transforms bacteria
If DNA from a disease-causing bacterium is added to the nucleus of a bacterium that normally does not cause disease, _____.
1 2 3 4
73%
8%7%12%
1. the new bacterium will cause the disease
2. the new bacterium will not cause the disease
3. the bacterium will die
4. the bacterium will be resistant to the disease
Bacteriophages
• Viruses that infect bacteria
• Consist of protein and DNA
• Inject their hereditary material into bacteria
Bacteriophages
Bacteriophages are _____.
1 2 3 4
6%0%
93%
1%
1. bacteria that infect viruses
2. bacteria that infect humans
3. viruses that infect bacteria
4. viruses that infect humans
Hershey and Chase’s Experiments
• Created labeled bacteriophages– Radioactive sulfur – Radioactive phosphorus
• Allowed labeled viruses to infect bacteria
• Where were the radioactive labels after infection?
virus particlelabeled with 35S
DNA (blue)being injected into bacterium
35S remainsoutside cells
virus particlelabeled with 32P
DNA (blue)being injected into bacterium
35P remainsinside cells
Fig. 9-2, p.139
Hershey and Chase Results
35S remains outside cells
32P remains inside cells
Structure of DNA
2nm diameter overall
0.34 nm between each pair of bases
3.4 nm length of each full twist of helix
In 1953, Watson and Crick showed that DNA is a double helix
Watson and Crick
Watson-Crick Model
• DNA molecule is a double helix
• Consists of two nucleotide strands that run
in opposite directions
• Strands are held together by hydrogen
bonds between bases
• A binds with T, C binds with G
Structure of Nucleotides in DNA
• Each nucleotide consists of– Deoxyribose (5-carbon sugar)
– Phosphate group
– A nitrogen-containing base
• There are four bases:– Adenine, Guanine, Thymine, Cytosine
Nucleotide Bases
phosphate group
deoxyribose
ADENINE (A)
THYMINE (T)
CYTOSINE (C)
GUANINE (G)
Composition of DNA
• Amount of adenine relative to guanine
differs among species
• Amount of adenine always equals amount of thymine, and amount of guanine always equals amount of cytosine
A=T and G=C
Rosalind Franklin’s Work
• Expert in x-ray crystallography
• Used technique to examine DNA fibers
Concluded that DNA was some sort of helix
The double-helix structure of the DNA molecule was discovered by _____.
1 2 3 4
58%
34%
7%
0%
1. Watson and Crick
2. Wilkins
3. Franklin
4. all of the choices
DNA Structure Allows It to Duplicate
• Two nucleotide strands held together by hydrogen
bonds
• Hydrogen bonds between two strands are easily
broken
• Each single strand serves as template for new
strand
2-nanometer diameter overall
0.34-nanometer distance between each pair of bases
3.4-nanometer length of each full twist of the double helix
In all respects shown here, the Watson–Crick model for DNA structure is consistent with the known biochemical and x-ray diffraction data.
The pattern of base pairing (A only with T, and G only with C) is consistent with the known composition of DNA (A = T, and G = C).
Fig. 9-6, p.141
DNA Models
In 1952, Franklin reported that the DNA molecule was a double helix with a
backbone formed of _____.
1 2 3 4
62%
16%12%10%
1. phosphate groups
2. purines
3. pyrimidines
4. nitrogen-containing bases
Patterns of Base Pairing
• A to T
• G to Cone base pair
or or
DNA Replication
newnew old old
• Each parent
strand remains
intact
• Every DNA
molecule is half
“old” and half
“new”
Base Pairing during
Replication
Each old strand is template for new complementary strand
Which of the following is a correct pairing of nitrogen-containing bases in DNA?
1 2 3 4
90%
3%3%4%
1. A = T
2. T = G
3. C = A
4. G = A
Enzymes in Replication
• Enzymes unwind the two strands and
complementary base pairs unzip
• DNA polymerase attaches new
complementary nucleotides
• DNA ligase fills in gaps
• Enzymes wind two strands together
DNA Repair
• Mistakes can occur during replication
• DNA polymerase reads correct
sequence from complementary strand
and, together with DNA ligase, repairs
mistakes in incorrect strand
In DNA replication, a permanent alteration in the DNA sequence is called a _____.
1 2 3 4
9%2%5%
84%1. genetic code
2. mutation
3. proofreading error
4. semiconservative replication
Which of the following statements about DNA is true?
1 2 3 4
0%
97%
2%2%
1. changes in DNA can be inherited by future generations
2. the term DNA stands for deoxyribonucleic acid
3. DNA codes all information needed to produce a human being
4. all of the choices
DNA Sequencing
• Order of fluorescent bands indicates DNA sequence
DNA Fingerprints
• Unique array of DNA fragments
• Inherited from parents in Mendelian
fashion
• Even full siblings can be distinguished
from one another by this technique
Analyzing DNA Fingerprints
• DNA is separated by gel electrophoresis
• Pattern of bands is used to
– Identify or rule out criminal suspects
– Identify bodies
– Determine paternity
A DNA Fingerprint
Clones
Cloning
• Making a genetically identical copy of
an individual
• Researchers have been creating clones
for decades
• Clones can be created by embryo
splitting (artificial twinning)
• In nucleus of differentiated cells, most DNA is
turned off
• Some DNA is turned on when nucleus is
transferred to egg cell
• New organism is genetically identical to donor of
nucleus
Clones from Adult Cells
Nuclear Transfer
• Nucleus of egg replaced with nucleus of adult cell
More Clones
• Numerous species been clonedMice, pigs, cattle, cats, etc.
• Most cloning attempts are still unsuccessful
• Many clones have defects
• Clones may vary in their phenotype
More Clones
Stem Cells
• Embryonic
• Adult
Embryonic Cells
I’m familiar with the arguments about stem cell research.
True
False
50%50%
1. True
2. False
Stem cell research is morally/ethically objectionable
I agre
e
I disa
gree
50%50%1. I agree
2. I disagree