Transcript Competency 4 Analyze and explain the structures and

Competency 4
Analyze 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
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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
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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
division
b. 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
G1 phase (gap)periods of growth
S phase (synthesis)DNA synthesized
(duplicated)
G2 phase (gap)Organelles produced.
M phase (mitosis)division of cell nucleus
and afterwards
CYTOKINESIS
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.
MEIOSIS
Reduction-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
n=23
human
sex cell
sperm
n=23
n=23
2n=46
diploid (2n)
n=23
n=23
haploid (n)
n=23
Meiosis I
Meiosis II
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Oogenesis
n=23
human
sex cell
egg
Haploid
(1n)
n=23
2n=46
diploid (2n)
Meiosis I
Polar
Bodies
(die)
n=23
Meiosis II
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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 I
b. Metaphase I
c. Anaphase I
Prophase I
d. Telophase I
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Prophase I
Longest and most complex phase
(90%).
Chromosomes condense.
Synapsis occurs - Homologous
chromosomes come together
to form a tetrad. (Crossing Over)
Tetrad is two chromosomes
or four chromatids (sister and nonsister 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
Tetrad
variation
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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
Homologs separate
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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
cytokinesis
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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 equator
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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)
1n Sperm cell
fertilizes 1n egg
to form 2n zygote
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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:
•
•
•
•
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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.