competency 4 analyze and explain the structures and functions of the levels of biological...

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.