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UNIT 2 OBJECTIVES
CHAPTER 7 : A TOUR OF THE CELL
1. Distinguish between prokaryotic and eukaryotic cells.
Prokaryotic cells lack a nucleus and organelles – they are purely DNA ; exp. Bacteria. Eukaryotic
cells are animal and plant cells.
4. Describe the structure and function of the nucleus, and briefly explain how the nucleus
controls protein synthesis in the cytoplasm.
The nucleus contains most of the genes that control the cell. Inside the nucleus the DNA is organized along
with proteins called chromatin. A nuclear envelope encloses the nucleus, separating it from the cytoplasm.
The nuclear envelope is a double membrane. The nuclear side of the envelope is lined by the nuclear
lamena, a netlike array of protein filaments than maintain the shape of the nucleus. The entire region
bounding the cell is the cytoplasm.
5. Describe the structure and function of a eukaryotic ribosome.
Ribosomes are the sites where cells assemble proteins. They do so in two cytoplasmic locals. Free
ribosomes are suspended in the cytosol, while bound ribosomes are attached to the outside of the ER
structure.
6. List the components of the endomembrane system, describe their structures and
functions and summarize the relationships among them.
The endo membrane system includes the nuclear envelope (separates the nucleus from the cytoplasm) ,
endoplasmic reticulum (functions in diverse metabolic processes) , golgi apparatus (sorts and ships cells’
products) , lysosomes (break down cell macromolecules for recycling) , various kinds of vacuoles, and the
plasma membrane. These membranes are not alike in structure, rather, they are related either through
direct physical continuity or the transfer of membrane segments through the movement of tiny vesicles.
7. Describe the vacuole & list types of vacuoles
Vacuoles have various functions in cell maintenance . A plant cells central vacuole functions in storage,
waste disposal, cell growth and protection.
8. Explain the role of peroxisomes in eukaryotic cells.
Peroxisomes consume oxygen in various metabolic functions. They are organelles that break down
various substances, producing H2O2 as waste.
9. Describe the structure & function of a mitochondrion
.The mitochondrion is the site of cellular respiration in eukaryotic cells. Its outer and inner membrane is
folded into the cristea.
11. Identify the three functional compartments of a chloroplast
The chloroplast is the site of photosynthesis. It is made up of membranes that surround the fluid stroma,
which contains thylakads, often stacked in grama.
12. Describe probable functions of the cytoskeleton.
Gives mechanical support to the cell and helps maintain its shape. It also enables it to change its shape,
like a scaffold the cytoskeleton can be dismantled in one part of the cell and reassembled in a new
location.
13. Describe the structure, monomers and functions of microtubules, microfilaments and
intermediate filaments.
The cytoskeleton is constructed from at least 3 types of these fibers. Microtubules are found in the
cytoplasm of all eukaryotic cells. They shape and support the cell and also act as tracks along which
organelles equipped with motor molecules can move. Microfilaments are the thinnest of these filaments and
intermediate are collections of fibers whose diameters fall in the middle range.
14. Explain how the ultra structure of cilia and flagella relates to their function.
In eukaryotes, a specialized arrangement of macrotubules is responsible for the beating of the flagella and
cilia, locomotive appendages that protrude from some cells Ex: Sperm of animals
17. Describe the structure of intercellular junctions found in plant and animal cells, and
relate their structure to function.
TIGHT JUNCTIONS : intercellular junction that prevents leakage of materials between cells.
DESMOSOMES: function as anchors; act as spot welds to hold together tissues that undergo considerable
stress. Ex: Skin/ heart tissues.
GAP JUNCTIONS: allows the passage of materials or current between cells (ions and small molecules);
prevents cytoplasm’s of each cell from mixing.
CHAPTER 8: MEMBRANE STRUCTURE AND FUNCTION OVERVIEW
1. Describe the function of the plasma membrane.
The plasma membrane controls traffic in and out of the cell it has selective permeability; that is it allows
some substances to outer more easily than others.
5. Describe the fluid properties of the cell membrane and explain how membrane fluidity
is influenced by membrane composition.
The cell membrane is made up of a layer of phospholipid is polar (attracted to water) its tail non-polar
(This polarity allows the movement of water to move between the membrane.
6. Explain how hydrophobic interactions determine membrane structure and function.
A membrane is held primarily by hydrophobic reactions- weaker than covalent bond. These bonds keep it
flexible. The membrane remains fluid as temperature decreases, until finally, at some critical temperature,
it solidifies.
7. Describe how proteins are spatially arranged in the cell membrane and how they
contribute to membrane function.
Proteins determine most of the membranes specific functions
8. Describe factors that affect selective permeability of membranes.
The hydrophobic core of the membrane impedes the transport of ions and polar molecules, which of
hydrophilic. Hydrophobic molecules can dissolve is the membrane and cross it with ease membrane are
permeable to specific ions and even certain polar molecules.
9. Define diffusion; explain what causes it and why it is a spontaneous process.
Diffusion is the tendency for molecules of nay substance to spread out into available space. Molecules have
intrinsic kinetic energy called thermal motion or heat. The result of thermal motion is diffusion.
10. Explain what regulates the rate of passive transport.
Diffusion or passive transport, in the absence of other forces, a substance will diffuse from where it is more
concentrated to where it is less concentrated.
12. Define osmosis and predict the direction of water movement based upon differences in
solute concentration.
Osmosis is the diffusion of water across a membrane from the hypotonic solution (less concentrated to the
hypertonic solution (less concentrated)
14. Describe how living cells with and without walls regulate water balance.
The animal cell has no rigid walls and cannot tolerate excessive uptake nor-excessive loss of water. Most
live in isotonic solutions, others develop osmoregulation.
16. Describe one model for facilitated diffusion.
Transport proteins aide in facilitated diffusion to a substrate, a membrane protein is specialized for the
solute it transports through the membrane.
17. Explain how active transport differs from diffusion.
Active transport is the pumping of solutes against their gradients.
20. Explain how large molecules are transported across the cell membrane.
21. Give an example of receptor-mediated endocytosis.
CHAPTER 12: THE CELL CYCLE OVERVIEW
.2. Overview the major events of cell division that enable the genome of one cell to be
passed on to two daughter cells.
Cell division is responsible for the continuity of life eukaryotic cell division consists of mitosis and
cytokenesis.
3. Describe how chromosome number changes throughout the human life cycle.
Each somatic all – any cell other then a sperm on overum- has the chromosomes as they split into material
and paternal sets there are 23 chromosomes
4. List the phases of the cell cycle and describe the sequence of events that occurs during
each phase.
MITOSIS
G1 – period of growth
S – DNA duplication
G2 – period of growth
Cytokinesis – the cell separates
5. List the phases of mitosis and describe the events characteristic of each phase.
PROPHASE- thicken into chromosomes, centerpiece develops centromere
METAPHASE- original chromosomes arrange themselves in the middle
ANAPHASE- chromosomes split in half and go to separate sites, pulled by spindle fibers
TELOPHASE- nucleus separate
6. Recognize the phases of mitosis from diagrams or micrographs.
(see notes for diagram)
8. Describe what characteristic changes occur in the spindle apparatus during each phase of
mitosis.
PROPHASE – spindle fibers move to the sides of the separating cell
METAPHASE – spindle fibers attach to the chromosomes arranged in the center
ANAPHASE – spindle fibers pull the chromosomes to the side of the cells
TELAPHASE – spindle fibers retreat
10. Compare cytokinesis in animals and plants.
Cytokenesis divides the cytoplasm. Implant alls a plant cell develops between the two forming cells. In
animal cells a cleavage develops and pinches the two cells.
11. Describe the process of binary fission in bacteria and how this process may have
evolved to mitosis in eukaryotes.
14. Explain how abnormal cell division of cancerous cells differs from normal cell division.
Cancer cells elude normal regulation and divide out of control, forming tumors.