Download - 1 st Semester Review
1st Semester Review
Cell Structure and Function
Cell Theory
A. Nature of Cells1. Cell theory
a. cell is the smallest unit that still has the characteristics of life.
b. new cells arise from preexisting cells
c. all organisms are comprised of one or more cells.
2. General aspects of cellsa. plasma membranes separate cells from their environment.b. DNA is the hereditary materialc. cytoplasm contains the organelles of the cell.
3. Types of cellsa. prokaryotes: ancient lineage, no nucleusb. eukaryotes: “true nucleus” and membrane bound organelles.
Eukaryotic Cells
A. Organelles1. all eukaryotes contain a nucleus and organelles.2. organelles form compartments in the cytoplasm of the cell3. compartmentalization = specialization4. reactions may be separated and regulated
Plant Cell
Animal Cell
Characteristics of Life
6 Characteristics of Living Organisms
Food getting – ability to get food either by catching it or
making it
Respiration – using oxygen to turn food into
energy (ATP)
Excretion – getting rid of the waste
(CO2, H2O, urea …)
Growth and Development – cell division, aging
Response – reacting to outside stimulus ex. light, temperature …
Reproduction – can make more cells or organisms
Robert Hooke describes the first
cells in 1665.
Antony Van Leeuwenhoek discovered
the first protozoa in 1674. He saw bacteria 9 years later.
In 1838 Theodor Schwann came up with the Cell Theory which
states:
1. All organisms are made up of 1 or more cells.
2. The cell is the basic unit of all living things.
3. Only living cells can produce new living cells.
Cells are the basic unit of all living things ex. unicellular or multicellular
LEVELS OF ORGANIZATION
Tissue is made up of like cells that perform a specific function ex. blood, bone, muscle
Organs are made up of different tissues that work together to perform a specific function ex. Heart = nerve, blood & muscle tissue
LEVELS OF ORGANIZATION
Body systems are made up of organs that work together
ex. digestive = esophagus – stomach - small intestine - large intestine - rectum
ex. circulatory, respiratory, nervous
Organisms are made up of body systems that work together for life
ex. you, paramecium, frog, trees
Scientific Method
• Science: a way of studying the world in order to understand how it works.
• Biology: the study of living things– Biology is used in medicine, veterinary
sciences, ecology, and genetics.– Biological knowledge is used to fight diseases
such as the flu, pneumonia, and AIDS
Science is a search for knowledge
• Science is used to solve problems that affect our lives.
• Hypothesis: a testable explanation for an observation
• Prediction: what you expect to happen IF your hypothesis is correct
• The controlled test of a hypothesis is called an experiment.
• In a CONTROL EXPERIMENT, a group that HAS NOT been exposed to the variable causing an effect is compared to a group that HAS BEEN exposed to the variable.
• The group NOT exposed to the variable is called the CONTROL GROUP.
• The VARIABLE is the factor you are testing that causes some effect.
• Theory: a unifying explanation for a broad range of observations – generally accepted as true.
• Science requires continued verification of hypothesis
• All Scientific theories can be overturned by new evidence.
SCIENTIFIC METHOD• The scientific Method is a systematic study of a question or
problem. 7 steps1. State the Problem2. Observations3. Gather Data4. Hypothesis5. Experiment6. Analyze data7. Draw a Conclusion8. **Repeat to ensure there were no mistakes**
Biochemistry
Elements and Atoms• Matter is anything that has mass and takes up space.• Atoms are the basic building blocks of all matter.• Elements are basic substances that cannot be broken
down into other substances.• Molecules are formed by the joining of atoms of two
or more elements. (smallest combination that cannot be divided without changing its chemical and physical properties)
• Compounds are composed of atoms of different elements chemically combined.
Atoms
• Atom consists of three subatomic particles called:Protons: positive chargeNeutrons: neutral/no chargeElectrons: negative charge
• The center of an atom is called the nucleus which consists of protons and neutrons.
Organic Substances/components
• Carbohydrates: made up of simple sugars• Proteins: made up of amino acids • Lipids: made up of a glycerol and at least 1
fatty acid• Nucleic Acids: made up of nucleotides
Organic Substances – contain Carbon and Hydrogen
Enzymes
• Enzymes are proteins that are used by the cell to speed up and regulate metabolic reactions.
• Enzymes are biological catalysts that remain unchanged by the reaction.
Organic SubstancesCarbohydrate
sProteins Lipids Nucleic Acids
SugarsStarches
MeatsHormones
MuscleHairNails
EnzymesBlood Cells
FatsOils
Waxes
DNARNA
Viruses!
Viruses are microscopic particles that invade the cells of plant, animals, fungi, and bacteria.
Bacteriaphage AIDS Virus
1. A virus is not a cell. A typical virus is composed of a core of genetic material surrounded by a protein coat. The protein coat protects the virus and enables it to invade its host cell.
2. In many viruses, DNA is the genetic material. Other viruses have RNA.
3. Viruses are parasitic and can reproduce only inside the cells of their host. This makes viruses very different from bacteria and protists.
AIDS Virus
In the Lysogenic Cycle:
1. Viral DNA merges with Cell DNA and does not destroy the cell. 2. The Virus does not produce progeny. 3. There are no symptoms of viral infection. 4. Temperate viral replication takes place.
Differences Between Lytic and Lysogenic Cycles
In the Lytic Cycle:
1. Viral DNA destroys Cell DNA, takes over cell functions and destroys the cell.
2. The Virus replicates and produces progeny phages. 3. There are symptoms of viral infection. 4. Virulant viral infection takes place.
•Some bacteria are autotrophs. •Autotrophic organisms make their own food by using simple molecules.
Autotrophs and Heterotrophs
•Most bacteria cannot make their own food and are therefore heterotrophs. •Many feed on dead animals and animal wastes; dead plants; and fallen leaves, branches, and fruit.
PHOTOSYNTHESIS/CELLULAR RESPIRATION
Energy in Living Systems
I. All organisms need energy I. The sun is the first and largest source of energy
II. Autotrophs
I. Organisms that gather their own energy
III. Heterotrophs
I. Organisms that gather energy from other organisms
Photosynthesis –Sun Energy
• Photosynthesis– In the chloroplasts
• Steps– Absorption of Light
• Energy is captured from the sunlight– Electron Transport Chain
• Light energy is converted to chemical energy ATP– Calvin Cycle
• ATP powers the formation of organic compounds
Photosynthesis:Energy from the Sun
Cellular EnergyI. Energy from food is trapped in ATP
I. Aerobic reactionI. Need Oxygen
II. Anaerobic reaction
I. Oxygen is not needed II. In Mitochondria
III. Plant and Animal Cells
C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
Cellular Respiration: Energy from food!!
Movement of Molecules
Osmosis
Passive TransportI. Requires NO energy
I. DiffusionI. Molecules move from HIGH concentration
to LOW concentration.
Passive Transport
II. OsmosisI. Diffusion of water across a biological membraneII. Helps cell maintain homeostasis
I. Maintaining stable conditionIII. Three examples:
Isotonic Solution[Water in] = [Water out] Cell is Happy
Hypotonic Solution[Water in] < [Water out] cell swells and blows up
Hypertonic Solution[Water in] > [Water Out] Cell Shrinks
Active TransportI. Requires Energy (ATP)
I. Some molecules are not easily diffused across membrane
II. Proteins embedded in membrane are used
Transport of Large Stuff
I. EndocytosisI. Cell takes “in” materials
II. ExocytosisI. Expulsion of material “out” of cell
Endocytosis
Exocytosis
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Cellular Division
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DNA ReplicationDNA must be
copied or replicated before cell division
Each new cell will then have an identical copy of the DNA
Original DNA strand
Two new, identical DNA strands
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KaryotypeA picture of the
chromosomes from a human cell arranged in pairs by size
First 22 pairs are called autosomes
Last pair are the sex chromosomes
XX female or XY male
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Abnormal Karyotype• Karyotypes can be used to examine an individual’s chromosomes and identify possible abnormalities in chromosome number.
• There should be only two copies of the #21 chromosome
• Instead there are three– This called trisomy/(non-
disjunction)– This occurs when
chromosomes in sex cells do not separate properly. Individuals with this abnormality do not develop properly
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Five Phases of the Cell Cycle
G1 - primary growth phaseS – synthesis; DNA
replicatedG2 - secondary growth
phasecollectively these 3 stages are called interphase
M - mitosisC - cytokinesis
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Four Mitotic Stages
ProphaseMetaphaseAnaphaseTelophase
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CytokinesisCleavage furrow in animal cell
Cell plate in plant cell
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Facts About Meiosis
Daughter cells contain half the number of chromosomes as the original cell
Produces gametes (eggs & sperm)
Occurs in the testes in males (Spermatogenesis)
Occurs in the ovaries in females (Oogenesis)
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Start with 46 double stranded
chromosomes (2n)After 1 division - 23 double stranded chromosomes (n)After 2nd division - 23 single stranded chromosomes (n)
Occurs in our germ cells that produce gametes
More Meiosis Facts
DNA & RNA
Parts and What-not
DNA/ RNA Notes•DNA- deoxyribonucleic acid, the material that contains the information that determines inherited characteristics.
I. Found: inside the nucleus of a cellII. Job: makes proteinsIII. Structure: double helix- two strands twisted around each other like a spiral staircase.IV. Nucleotides: subunits that make up DNA
A. There are 3 parts to each Nucleotide1. Phosphate group2. 5- carbon sugar molecule3. Nitrogenous base group
Adenine (A) Guanine (G) Thymine (T) Cytosine (C)
4. Chargaff< A=T , G=C•DNA Replication- Replication results in two identical DNA strands (p. 198)
A. The two original DNA strands separateB. DNA polymerases add complementary nucleotides to each strandC. Two DNA molecules from that are identical to the original DNA molecule.
•RNA- ribonucleic acid- present in all living cells and plays a role in protein synthesisI. Different than DNA in 3 ways
A. single strand of nucleotidesB. sugar is Ribose ( in DNA its DeoxyriboseC. Like DNA it has 4 bases
1. Adenine (A)2. Guanine (G)3. Cytosine (C)4. Uracil (U) – This Takes the place of Thymine (T)5. A=U , G=C
II. There are 3 types of RNAA. mRNA- messenger RNA- carries instructions for making proteins out of the nucleus to the site of TranslationB. tRNA- transfer RNA- helps translate the mRNA’s message so that amino acids can be made to construct the proper proteinC. rRNA – ribosomal RNA-helps tRna translate the mRNA’s message.
From Genes to ProteinsAll About RNA
Transcription
• Takes place in the nucleus.• Starts at a ‘start’ signal and ends with a ‘stop’
signal.• Requires RNA polymerase
– Opens DNA– Adds complementary nucleotides of RNA
•mRNA then leaves through the nuclear pores out to the cytoplasm where it settles on a ribosome.
Genetic Code
• The instructions for making proteins are written as a series of three-nucleotide sequences on the mRNA called codons.
• Each codon codes for an amino acid or signals a start or stop for translation.
• AUG = start• UAG = stop
Translation• Takes place in the cytoplasm on the
ribosomes.• tRNA molecules are single strands of RNA that
temporarily carry an amino acid on one end.• Each tRNA contains an anticodon for the
mRNA’s codon.• The anticodon is a three-nucleotide sequence
that is complementary to a particular mRNA codon.
Translation continues…
• When a tRNA’s anticodon matches up with the codon of mRNA, it drops off its’ amino acid.
• Each amino acid forms a peptide bond with the previous amino acid which results in the production of a protein.