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Chapter 4 - Cell Structure
Terms in this set (77)
1665 by Robert Hooke
Cells were discovered in ___________ by __________________.
1. All organisms are composed of cells
2. Cells are the smallest living things
3. All cells arise only from pre-existing cells
Lee: cells are basic units of organization; life processes take place in the cell
What are the three principles of cell theory?
Most cells are relatively small due to reliance on diffusion of substances in and out of cells.
Why is cell size limited?
1. Surface area available
3. Concentration gradient
What is rate of diffusion affected by?
As a cell gets larger its volume increases at a faster rate than its surface area
Explain the surface-area-to-volume ratio
The minimum distance two points can be a part and still be distinguished as two separate parts
What is resolution?
1. Light microscopes
2. Electron microscopes
What are the two types of microscopes?
1. Centrally located in genetic material
2. Cytoplasm — Semi fluid matrix of organelles and cytosol
3. Plasma membrane — Phospholipid bilayer
What three fundamental ways do all cells resemble one another?
1. Simplest organisms
2. Lack a membrane-bound nucleus — DNA is in the Nucleoid
3. Cell wall is outside of the plasma membrane
4. Contain ribosomes
5. No membrane bound organelles
6. Two domains
What are the six characteristics of prokaryotic cells?
1. Most are encased by a strong cell wall — composed of peptidoglycan
2. Protect the cell, maintain its shape, and prevent excessive uptake or lots of water
3. Susceptibility of bacteria to antibiotics often depends on the structure of their cell walls
4. Some secrete a jellylike protective capsule
What are the characteristics of bacterial cell walls?
1. Do not have peptidoglycan cell walls —Composed of polysaccharides and proteins
2. Membrane lipids are distinctly different from lipids in bacteria
3. DNA replication and protein synthesis is similar to eukaryotes
What are the characteristics of Archaea?
Long thread like structures protruding from the surface of a cell and used in locomotion
Define the Flagella
1. Present in some prokaryotic cells — May be one or more or none
2. Used for locomotion
3. Rotary motion propels the cell
4. Rotary motor uses energy stored in protein gradient
What are the characteristics of Flagella?
1. Possess a membrane-bound nucleus
2. More complex than prokaryotic cells
3. Hallmark is compartmentalization
-Achieved through use of membrane-bound organelles and endomembrane system
4. Possess a cytoskeleton for support and to maintain cellular structure
What are the characteristics of eukaryotic cells?
1. Plasma membrane — Where the semi fluid matrix is
2. Cytoplasm — Semi fluid area
3. Organelles — We are specialized structures lie within the cell
4. Nucleus — where DNA is
What are the features of eukaryotic cells?
1. Repository of the genetic information
2. Most eukaryotic cells possess a single nucleus
3. Nucleolus is the region where ribosomal RNA synthesis takes place
4. Has a nuclear envelope that consists of 2 phospholipid bilayers and a nuclear pores that control passage in and out
5. In eukaryotes, the DNA is divided into multiple linear chromosomes
- Chromatin is chromosomes plus protein
What are the characteristics of a nucleus?
The ________________ has a double membrane called the ________________.
1. Cell's protein synthesis machinery
2. Found in all cell types in all three domains — Bacteria, Archaea and Eukarya
3. Contains ribosomal RNA (rRNA) — protein complex
4. Proteins synthesis requires messenger RNA (mRNA) and transfer RNA (tRNA)
5. Ribosomes may be free in cytoplasm or associated with internal membranes
What are the characteristics of ribosomes?
rRNA have _______ subunits that join when the are _______________ making _______________.
_______________ are among the most complex molecular assemblies found in cells.
Carries down the coding information from DNA
What does mRNA do?
Carries the amino acids
What does tRNA do?
rRNA actually makes the proteins during protein synthesis
Which form of RNA actually makes the proteins?
What do ribosome subunits carry?
What is the main function of ribosomes?
1. Series of membranes throughout the cytoplasm
2. Divides so into compartments were different cellular functions take place
3. Is one of the fundamental distinctions between eukaryotes and prokaryotes
What are the characteristics of the Endomembrane system?
1. Rough endoplasmic reticulum (RER)
2. Smooth endoplasmic reticulum (SER)
What are the two types of endoplasmic reticulum?
1. The many attached ribosomes to the membrane gives a rough appearance
2. Synthesis of proteins to be secreted, sent to lysosomes or plasma membrane
A site of protein synthesis
What are the characteristics of rough endoplasmic reticulum (RER)?
1. Relatively few bound ribosomes
2. Serves a variety of functions
What are the characteristics of smooth endoplasmic reticulum (SER)?
The cells function
What does the ratio of RER to SER depend on?
The majority of ________________ are found in smooth reticulum.
What part of the cell is like a post office?
*Molecules synthesized at one location and used at another within the cell or outside of it
What functions does the Golgi Apparatus to do?
Front is cis face (usually located near ER)
Back is trans face (transports to vesicles)
The Golgi Apparatus has a front face known as _____________ and a back face known as _____________.
1. Membrane bound digestive vesicles
2. Arise from Golgi Apparatus
3. Where enzymes catalyze breakdown of macromolecules
4. Destroy cells or foreign matter that the cell has engulfed by phagocytosis
What are the characteristics of lysosomes?
Variety of enzyme-bearing membrane-enclosed vesicles
What are microbodies?
It's an important type of micro body. It digest and detoxifies enzymes
What is peroxisome and what does it do?
From the hydrogen peroxide it that is produced as a byproduct
How do microbodies (perxisomes) get their name?
Large cylindrical complexes
What are Proteosomes?
Puts a tag on a protein and as it enters it recycles it and it comes out as an amino acid or polypeptide. Can handle miss folded damaged or no longer needed proteins.
What do Proteosomes do?
Membrane-bound structures found in plants. Has various functions depending on the cell type.
What is a vacuole and where is it found?
1. Central vacuole in plants
2. Contractile vacuole of some fungi and protists
3. Storage vacuole
What are the types of vacuoles?
Stores in dissolved substances, can be expanded to increase its pressure gradient.
What does a vacuole do?
In ALL types of eukaryotic cells
Where is mitochondria found?
Energy processing organelles
Mitochondria and chloroplasts are both _________________________.
1. Both are surrounded by a double membrane
2. Both contain their own DNA
3. Both have their own protein synthesis machinery
What are the structural similarities between mitochondria and chloroplasts?
They are both intimately involved in energy metabolism
What are the functional similarities between mitochondria and chloroplasts?
1. Outer membrane — Smooth
2. Inner membrane — Inner space
3. Cristae — Layers of inner membrane that are folded
What are the membranes that mitochondria are bound by?
1. Found in all types of eukaryotic cells
2. Bound by membranes
3. Have proteins that carry out oxidative metabolism
4. Have their own DNA
List the key characteristics of mitochondria
1. Organelles present in cells of plants and some other eukaryotes
2. Contain chlorophyll for photosynthesis
3. Surrounded by two membranes
4. Have thylakoids — membraneous sacs within inner membrane with Grana (Stacks of thylakoids)
5. Have their own DNA
List the characteristics of chloroplast
A cell like organelle present in algae and plants that contain chlorophyll and carries out photosynthesis
What is a chloroplast?
1. ATP (Adenosine Triphosphate — Energy)
Chloroplast use light to generate what?
1. Network of protein fibers (3 types) found in all eukaryotic cells.
- Fibers support the shape of the cell and keeps organelles in fixed locations
2. Dynamic system - constantly forming, changing and disassembling
What are the characteristics of cytoskeleton?
1. Actin filaments (microfilaments)
3. Intermediate filaments
Found in the cytoskeleton
What are the three types of fibers and where are they found?
1. Composed of 2 protein chains loosely twined together
2. Exhibit polarity
3. Designate the growth of a filament
4. Move by crawling "pinching" through the cell
What do actin filaments do within the cytoskeleton?
1. The largest of the cytoskeleton elements
2. They are hello
3. Facilitate movement of cell and materials within the cell
What are the characteristics of the microtubules within the cytoskeleton of cells?
1. Between the size of the actin filaments and microtubules
2. Very stable — most durable of the fibers
What are the characteristics of the intermediate filaments with in the cytoskeleton?
1. Barrel shaped in nature
2. Microtubule — Organization center
3. Play a part in cell division
4. Rigid, can be at right angles and occur in pairs
5. Composed of 9 triplets
6. Plants and fungi usually lack centrioles
What are the characteristics of centrosomes?
1. Essentially ALL cell motion is tied to the movement of actin filaments, microtubules or both
2. Some cells crawl using actin filaments
3. Flagella and cilia have 9+2 arrangement of microtubules — 9 rings with 2 arms
Discuss sell movement as it relates to the cytoskeleton
1. Vesicles are transported along microtubules using motor proteins, they use ATP to generate force.
2. Vesicles are attached to motor proteins by connector molecules
3. The motor protein dynein moves the connected vesicle along microtubules
How do molecular motors function?
1. Many Protists use them to "swim"
2. Pairs of microtubules move past each other using arms composed of the motor protein dynein
3. The motor proteins dynein moves the connected vesicle along microtubules
What role does flagella and cilia play in cell movement?
3. Many Protists
Which eukaryotes have cell walls?
1. Found in plants, fungi in many protists
2. Different from prokaryotes
3. Plants and protists use cellulose
4. Fungi use chitin
5. Plants have primary and secondary cell walls
What are the characteristics of eukaryotic cell walls?
In animal cells because they lack cell walls
Where would you find the extracellular matrix (ECM) and why?
1. Secrete an elaborate mixture of glycoproteins into space around them
2. Collagen may be abundant
3. Forms a protective layer over cell surface
4. Integrins link ECM to cell's cytoskeleton which can influence cell behavior
What are the characteristics of extracellular matrix (ECM)?
Animal cells are surrounded by a ______________ that gives the cell ______________ and ________________.
What gives a cell its identity?
Most tissue-specific cell surface marker
What is a glycolipid?
Lipid tail with a carbohydrate head
What makes it a glycolipid?
1. Adhesive junction
2. Septate or tight junction
3. Communicating junction
List the 3 categories of cell connections
Mechanically attach the cytoskeleton of neighboring cells
What does the adhesive Junction do?
What are the 3 types of adhesive junctions?
They connect the plasma membrane's of adjacent cells in a sheet. They allow no leakage in sheet formation
How does a septate or tight Junction work?
It's a chemical or electrical signal that passes directly from one cell to another
How does a communicating in Junction work?
What is a communicating and junction in animals called?
What is a communicating junction in a plant called?
1. Specialized openings in plant cell walls
2. Where cytoplasm of adjoining cells are connected
3. Cells communicate through openings in the cell wall
What is Plasmodesmata?
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