competency 4 analyze and explain the structures and functions of the levels of biological...
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Competency 4Analyze and explain the structures and functions
of the levels of biological organization.
14 Questions on the state test from this competency
4a Differentiate among plant and animal cells and eukaryotic and
prokaryotic cells
Prokaryotic Cells
• No membrane bound nucleus• Organelles not bound by membranes• Bacteria
Eukaryotic Cells• Nucleus bound by membrane• Include fungi, protists, plant,
and animal cells• Possess many organelles
Protozoan
Know the functions of all major organelles and structures.
Cytoplasm• Viscous fluid containing organelles• components of cytoplasm
– Interconnected filaments & fibers – Fluid = cytosol– Organelles (not nucleus)– storage substances
Cytoskeleton• Filaments & fibers
• Made of 3 fiber types– Microfilaments– Microtubules– Intermediate filaments
• 3 functions:– mechanical support– anchor organelles– help move substances
Nucleus
• Control center of cell
• Double membrane
• Contains – Chromosomes– Nucleolus
DNA
• Hereditary material
• Chromosomes– DNA– Protiens– Form for cell division
• Chromatin
Nuclear Envelope
• Separates nucleus from rest of cell
• Double membrane
• Has pores
Nucleolus
• Most cells have 2 or more• Directs synthesis of RNA• Forms ribosomes
Endoplasmic Reticulum
• Helps move substances within cells
• Network of interconnected membranes
• Two types– Rough endoplasmic reticulum– Smooth endoplasmic reticulum
Rough Endoplasmic Reticulum
• Ribosomes attached to surface– Manufacture protiens– Not all ribosomes attached to rough ER
• May modify proteins from ribosomes
Smooth Endoplasmic Reticulum
• No attached ribosomes• Has enzymes that help build molecules
– Carbohydrates– Lipids
Golgi Apparatus
• Involved in synthesis of plant cell wall• Packaging & shipping station of cell
Lysosomes
• Contain digestive enzymes• Functions
– Aid in cell renewal– Break down old cell parts – Digests invaders
Vacuoles
• Membrane bound storage sacs• More common in plants than animals• Contents
– Water– Food– wastes
Ribosomes
*Site of Protein Synthesis (place where proteins are made)
*Found floating all in the cytoplasm and on the rough ER
Mitochondria
• Have their own DNA• Bound by double membrane• Break down fuel molecules (cellular respiration)
– Glucose– Fatty acids
• Release energy– ATP
Centrioles• Pairs of microtubular structures• Play a role in cell division
Chloroplasts
• Derived from photosynthetic bacteria (endosymbiosis)
• Solar energy capturing organelle
Photosynthesis• Takes place in the chloroplast• Makes cellular food – glucose
Cell Walls
• Found in plants, fungi, & many protists• Surrounds plasma membrane-provides rigidity• Plants – mostly cellulose• Fungi – contain chitin
Plasma Membrane• Contains cell contents and regulates what
enters and leaves the cell• Double layer of phospholipids & proteins
Phospholipids
• Polar– Hydrophylic head– Hydrophobic tail
• Interacts with water
Fluid-Mosaic Model
Membrane Proteins
1. Channels or transporters– Move molecules in one direction
2. Receptors – Recognize certain chemicals
Membrane Proteins
3. Glycoproteins – Identify cell type
4. Enzymes – Catalyze production of substances
Molecule Movement & Cells
• Passive Transport- does not require energy by the cell
• Active Transport- requires energy!!
Passive Transport
• No energy required
• Move due to gradient– differences in concentration, pressure, charge
• Move to equalize gradient– High concentration moves toward low concentration
Types of Passive Transport
1. Diffusion
2. Osmosis
3. Facilitated diffusion
Diffusion
• Molecules move to equalize concentration
Osmosis
• Special form of diffusion
• Fluid flows from lower solute concentration
• Often involves movement of water– Into cell– Out of cell
Solution Differences & Cells• solvent + solute = solution• Hypotonic
– Solutes in cell more than outside– Outside solvent will flow into cell
• Isotonic– Solutes equal inside & out of cell
• Hypertonic– Solutes greater outside cell– Fluid will flow out of cell
Facilitated Diffusion
• Differentially permeable membrane
• Channels (are specific) help molecule or ions enter or leave the cell
• Channels usually are transport proteins • No energy is used
Process of Facilitated Transport
• Protein binds with molecule• Shape of protein changes• Molecule moves across membrane
Active Transport
• Molecular movement• Requires energy (against gradient)• Example is sodium-potassium pump
Forms of Endocytosis• Phagocytosis – cell eating• Pinocytosis – cell drinking
Exocytosis• Reverse of endocytosis• Cell discharges material
Pseudopodia, Cilia & Flagella• All provide provide motility• Pseudopodia - extensions of the cytoplasm of an amoeba• Cilia
– Short, hair like projections– Used to move substances
outside human cells• Flagella
– Whip-like (tail) extensions– Found on sperm cells
4b Differentiate between types of cellular reproduction.
Cell Division- to solve the problem of small surface area to volume, a cell divides into two daughter cells
a. Cell replicates (copies) it’s DNA before divisionb. Rates vary from 30 minutes (bacteria) to many decades
Cell Division
A. Chromosomes- genetic information carried on chromosomes
1. Before cell division each chromosome is replicated (copied)
2. Each chromosome consists of two identical “sister” chromatids
3. Each pair of chromosomes attached to area called centromere
The Cell Cycle- Series of events that cells go through as they grow and divide
M phase (mitosis)- division of cell nucleus and afterwards CYTOKINESIS
S phase (synthesis)- DNA synthesized (duplicated)
G2 phase (gap)- Organelles produced.
G1 phase (gap)-periods of growth
Interphase - not part of mitosis
• “Normal cell life” • Cell division does not occur.• Chromatids (DNA) copy
themselves to make a full chromosome-during the S phase.
Mitosis- Division of Cell Nucleus and Cytokinesis. Divided into 4 phases
1. Prophase- First and longest phase.
• Chromosomes become visible
• Centrioles separate and migrate to opposite sides of nucleus
• Chromosomes attach to spindle fibers.
• Nuclear membrane breaks down
2. Metaphase- Chromosomes line up across the center of the cell
3. Anaphase
• Centromeres that join chromatids separate.
• Sister chromatids separate
• Chromosomes moves to opposite poles
4. Telophase-
• Condensed chromosome begin to disperse
• Nuclear envelope re-forms around cluster of chromosomes
• Nucleolus becomes visible
D. Cytokinesis- division of cytoplasm following mitosis
1. Animal cells- cell membrane drawn inward until cytoplasm is pinched into two nearly equal parts
2. Plant cells- cell plate forms midway between divided nuclei. Gradually develops into separating membrane. Eventually cell wall begins to appear.
B. Uncontrolled Cell Growth
1. Cancer- do not respond to signals that regulate growth of most cells. Form masses called tumors
2. Don’t respond to external growth regulators. Some may be genetic.
MEIOSISReduction-Division
Genetic Recombination
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Meiosis
A form of cell division by which GAMETES, with HALF the number of CHROMOSOMES, are produced.
DIPLOID (2n) HAPLOID (n) Meiosis is SEXUAL reproduction. TWO divisions (MEIOSIS I and MEIOSIS
II).
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Spermatogenesis
2n=46
humansex cell
diploid (2n)
n=23
n=23
Meiosis I
n=23
n=23
n=23
n=23
sperm
haploid (n)
Meiosis II56
Oogenesis
2n=46
humansex cell
diploid (2n)
n=23
n=23
Meiosis I
n=23egg
Haploid (1n)
Meiosis II57
Polar Bodies (die)
Interphase I Similar to mitosis interphase. CHROMOSOMES (DNA) replicate in the S phase Each duplicated chromosome consist of two identical
SISTER CHROMATIDS attached at their CENTROMERES. CENTRIOLE pairs also replicate.
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Meiosis I (four phases)
• Cell division that reduces the chromosome number by one-half.
• Four phases:a. Prophase Ib. Metaphase Ic. Anaphase Id. Telophase I
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Prophase I
Prophase I Longest and most complex phase
(90%). Chromosomes condense. Synapsis occurs - Homologous
chromosomes come togetherto form a tetrad. (Crossing Over)
Tetrad is two chromosomesor four chromatids (sister and non-sister chromatids).
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Crossing Over• Crossing over may occur
between non-sister chromatids.• Crossing over: segments of
nonsister chromatids break and reattach to the other chromatid.
• Causes Genetic Recombination
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Genetic Recombination
nonsister chromatids
variation
Tetrad
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Metaphase I• Shortest phase• Tetrads align on the equator.• Independent assortment occurs –
chromosomes separate randomly causing GENETIC RECOMBINATION
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Anaphase I
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Homologs separate
Telophase I
Each pole now has haploid (1n) set of chromosomes.
Cytokinesis occurs and two haploid daughter cells are formed.
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Telophase I
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cytokinesis
Meiosis II
No Interphase II or very short No DNA Replication Remember: Meiosis II is similar to mitosis
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Prophase II• Same as Prophase in
mitosis Nucleus & nucleolus
disappear Chromosomes condense Spindle forms
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Metaphase II
• Same as Metaphase in mitosis
Chromosomes (not homologs) line up at equator69
Anaphase II
• Same as Anaphase in mitosis• SISTER CHROMATIDS
separate
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Telophase II Same as Telophase in mitosis. Nuclei and Nucleoli reform, spindle disappears CYTOKINESIS occurs. Remember: FOUR HAPLOID
DAUGHTER cells are produced. Called GAMETES (eggs and sperm)
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1n Sperm cell fertilizes 1n
egg to form 2n zygote
Telophase II
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Binary fission is a type of cellular reproduction. Bacteria reproduce
asexually by binary fission.
Budding is another form of asexual reproduction.
• Hydra bud to form new hydra. Yeast cells undergo budding.
Vegetative propagation is a form of asexual reproduction in plants.
4c Describe and differentiate among the organizational levels of
organisms
Cells• The basic unit of structure and function in
the human body
• Examples may be nerve cells (neurons), blood cells, and bone cells.
Tissues
• A group of specialized cells that work together to perform the same function.
• There are four basic types of tissue in the human body:
Organs• A group of two or more different types of
tissue that work together to perform a specific function.
• For example, the heart is made of muscle and connective tissues which functions to pump blood throughout the body.
Systems• A group of two or more organs that work
together to perform a specific function.
• There are eleven different organ systems in the human body: circulatory, digestive, endocrine, excretory (urinary), immune, integumentary, muscular, nervous, reproductive, respiratory, and skeletal.
The levels of organization from simplest to most complex are:
• Cells• Tissues • Organs• System• Organism
4d Explain and describe how plant structures (vascular and
nonvascular) are related to the survival of plants.
Plants are either vascular or nonvascular. Plants cells that form tissues called xylem and phloem make up the vascular tissue. Xylem carries water throughout the plant, and phloem carries nutrients and food throughout the plant.
Nonvascular plants DO NOT have xylem or phloem or true roots, stems, or leaves. They are small because they have no way of transporting water around the plant.