Chapter 4 Test
Definition of cell: simplest collection of matter that can live
Why are cells small? Because they need to transport things across plasma membrane
Cells must be large enough to…house DNA, proteins, and other structures needed to survive and
reproduce; Need to remain small enough to allow for a surface-to-volume ratio that will allow adequate
exchange with the environment
The plasma membrane forms a flexible boundary between living cell and its surroundings
Phospholipids form a 2-layer sheet called a phospholipids bilayer in which:
-Hydrophilic heads face outward, exposed to water
- Hydrophobic tails point inward, shielded from water
Membrane proteins are either…. Attracted to membrane surface; embedded in phospholipid bilayer
Some proteins form tunnels to shield ions and hydrophilic molecules as they pass through hydrophobic
center of membrane
Other proteins serve as pumps, using energy to transport molecules into or out of cell
Are prokaryotic cells structurally simpler than Eukaryotic cells? Yes
List 2 types of Prokaryotic cells: Bacteria and Archaea
Both Prokaryotic and eukaryotic cells have: Plasma membrane and one+ chromosomes and ribosomes
Eukaryotic cells have Membrane-bound nucleus and # of other membrane-bound organelles
Prokaryotes have a nucleoid and no true organelles
The DNA of Prokaryotic cells is coiled into a region called nucleoid
Does a membrane surround the DNA in a prokaryotic cell? No
Can the surface of prokaryotic cells be surrounded by a wall? may Be surrounded by chemically complex
cell wall or have capsule surrounding cell wall
What do Flagella do? propel the cell through its liquid environment
What are Cilia and what does it do? short projections that help attach to other cells
4.4
The nucleus and ribosomes are involved in the genetic control of cell
The E.R., Golgi Apparatus, lysosomes , vacuoles, and peroxisomes are involved in the manufacture,
distribution, and breakdown of molecules
Mitochondria in all cells and chloroplasts in plant cells are involved in energy processing
Structural support, movement, and communication between cells are functions of the Cytoskeleton,
plasma membrane, and cell wall
Cellular metabolism -many chem activities, occurs within organelles
Almost all organelles/structures of animal cells are present in plant cells, a few exceptions exist;
Lysosomes and centrioles are not found in plant cells
Plant cells but not animal cells, have
-A rigid cell wall
- Chloroplasts
-Central Vacuole
The nucleus is the cell’s genetic control center
The Nucleus: contains most of the cell’s DNA
Controls cell’s activities by directing protein synthesis by making messenger RNA (mRNA)
DNA is associated with many proteins in structures called Chromosomes
The nuclear envelope is a double membrane and has pores that allow material to flow in and out of cell
The nuclear envelope is attached to a network of cellular membranes called the Endoplasmic Reticulum
The nucleolus is a structure in the nucleus and is the site of ribosomal RNA (rRNA) synthesis
Ribosomes make proteins for use in cell export and are synthesized from rRNA produced in Nucleolus
Free Ribosomes: Suspended in cytoplasm and involved in making proteins that function within
cytoplasm
Bound Ribosomes: attached to E.R. associated with Nuclear Envelope and with proteins packed in
certain organelles or exported from cell
Many organelles are connected through the endomembrane system
Some of these membranes are physically connected and some are related by the transfer of membrane
segments by tiny vesicles (sacs made of membrane)
The endomembrane system includes:
-Nuclear envelope
-Golgi Apparatus
- Plasma Membrane
-Endoplasmic Reticulum
- Lysosomes
-Vacuoles
Many of these organelles work together in the:
-Synthesis
-storage
-and export of molecules
Rough ER: lines the outer surface of membranes and makes membrane for itself and proteins destined
for secretions
Smooth ER: Involved in variety of diverse metabolic processes and produces enzymes important in
synthesis of Lipids, Oils, Phospholipids, and steroids
The Golgi Apparatus: finishes, sorts, and ships cell products
Lysosome: membranous sac containing digestive enzymes; help digest food particles engulfed by the
cell; help remove or recycle damaged parts of cell
Vacuoles function in general maintenance of cell
Vacuoles – large vesicles that have a variety of functions
Mitochondria -organelles that carry out cellular respiration in nearly all Eukaryotic cells
Chloroplasts - photosynthesizing organelles of all photosynthesizing eukaryotes
Mitochondria and chloroplasts have: DNA and Ribosomes
Photosynthesis is conversion of light energy from the sun to the chemical energy of sugar molecules
The Endosymbiont Theory proposes that Mitochondria and chloroplasts were formerly small
prokaryotes and they began living within larger cells
Cells contain a network of protein fibers called the Cytoskeleton which functions in structural support
and motility
Scientists believe that motility and cellular respiration result when the cytoskeleton interacts with
proteins called motor proteins
The Cytoskeleton is composed of 3 kinds of fibers, list the fibers: Microfilaments (actin filaments)
support the cell’s shape and are involved in motility; Intermediate Filaments reinforce cell shape and
anchor organelles; Microtubules (made of tubulin) give the cell rigidity and act as tracks for organelle
movement
When do cilia and flagella move? Cilia and Flagella move when microtubules bend
Some protists use cilia and flagella in locomotion, others use them to: sweep mucus out of lungs and in
animal sperms, which are flagellated
A Flagellum, longer than cilia, propels a cell by undulating whip-like motion
Animal cells synthesize and secrete an elaborate Extracellular Matrix (ECM) that
Helps hold cell together in tissues and
Protects and supports plasma membrane
3 types of cell junctions found in animal tissues:
-Tight Junctions: prevent leakage of extracellular fluid across a layer of epithelial cells
- Anchoring Junctions: fasten cells together into sheets
- Gap Junctions: channels that allow molecules to flow btwn cells
Plant cells have cell junctions called Plasmodesmata that serve in communication btwn cells