Chapter 4: Cells Flashcards
Cell Theory
Was developed in 19th century, and is recognized as the basic fact about life
What are the 3 components of Cell theory
- Cells are fundamental units of life
- All living organisms are composed of cells
- All cells come from preexisting cells
What is the volume of a cell?
The volume of a cell determines its rate of metabolic activity
What is the surface area of a cell?
The surface area of a cell determines the rate at which of substances can enter or leave a cell
Light Microscopes
Light microscopes use glass lenses and light. The highest resolution is 0.2 micrometers
Electron microscopes
They use an electron beam focused by magnets to illuminate a specimen.
What does scanning electron microscope show?
It shows surface features
What does transmission electron microscope show?
It shows internal details
Plasma membrane
Cell membrane
What is selective permeable barrier?
It blocks some substances while permits other substances to enter a cell
What does cell membrane do and have?
- It is important in communication and receiving signals
2. Cell membrane have proteins that protrude from the membrane to bind and adhere to adjacent cells or to a surface
What is the basic structure of a prokaryotic cell?
- It has a cell membrane
- Lacks membrane-bound organelles
- Have nucleoid, where their chromosomes are organized
- have circular chromosomes
- Have ribosome
What do all cells have?
They all have a plasma membrane, a cytoskeleton, and ribosomes
What are the two broad categories of bacteria-based pn early staining?
Gram positive and Gram negative
Gram positive
Plasma membrane surrounded by a thick peptidoglycan layer (a polymer of carbohydrates)
Gram negative
Plasma membrane surrounded by a thin peptidoglycan layer and an outer layer
What do all eukaryotic cell have?
They have a nucleus
They have a linear chromosome
They are 10-100 times bigger than prokaryotic cells
They contain membrane bound organelles that perform a certain function
What does the nucleus contain?
- It is the site of DNA storage and is the place where DNA is replicated and transcribed (RNA)
- It contains nucleolus
Nucleolus
A darkly stained region where ribosomes begin to be assembled from RNA and proteins
What is the nucleus surrounded by?
It is surrounded by 2 membranes that form the nuclear envelope
Nuclear Envelope
is composed of 2 double lipid bilayer that has a nuclear pore complex which is made of 456 proteins
What does the nuclear pore complex do?
- It decides what goes in and out of a cell
2. It controls movement of molecules between the nucleus and cytoplasm
What does a nucleus do with DNA?
The DNA inside a nucleus combines with proteins to form chromatin in long, thin threads of nucleic acids called chromosomes
Endomembrane System
Is a group of interrelated organelles of a cell
Endoplasmic Reticulum (ER)
Is a network of interconnected membranes in the cytoplasm with a large surface area
What are the two types of Endoplasmic reticulum? (ER)
Rough ER and smooth ER
Rough ER
Is the site of much protein synthesis, which occurs on ribosomes on its surface, which transport across a membrane
Smooth ER
Is where proteins and other molecules are chemically modified
Golgi Apparatus
Is composed of flattened sacs (cristernae) and small enclosed vesicles
What are the functions of the Golgi Apparatus?
- It concentrates, packages, and sorts protein before they’re sent to their cellular or extracellular destinations
- They add or remove carbohydrates or proteins
- Add sulfate groups and add signal peptides
Lysosomes
They originate from the Golgi apparatus
What are the functions of lysosomes?
- Contain hydrolases (digestive enzymes) that can break down macromolecules into smaller monomers
- break down viruses and bacteria
- involves in other cell processes including secretion, plasma membrane repair, cell signaling, and cellular metabolism
Mitochondrion
Plural of mitochondria and are the cell’s energy source
What’s in the mitochondria structure?
They are bound by 2 lipid membranes
Mitochondria outer membrane
They have large pores, and most substances can pass through it
Mitochondria inner membrane
They have extensive folds called cristae to increase surface area.
Mitochondrial matrix
Is the fluid inside the mitochondria inner membrane and contains enzymes, DNA, and ribosomes
Chloroplasts
Contains the green pigment chlorophyll and is the site of photosynthesis
Photosynthesis
Is the process of converting light energy into chemical energy
What is the structure of a chloroplast?
It is enclosed within 2 membranes
Vacuoles
A space within the cytoplasm of a cell, which is mainly found in plants and fungi
What are the functions of vacuoles?
- Stores poisonous and distasteful waste that may deter herbivores
- Water enters the vacuole by osmosis, creating a turgor pressor
Turgor Pressure
Is the force within a cell that pushes the plasma membrane against the cell wall
Cytoskeleton
Is composed of microtubules, intermediate filaments, and microfilaments that support the cell and is involved in cell and organelle movement
What are the functions of the cytoskeleton?
- support the cell and maintains its shape
- holds cell organelles and other particles in position within the cell
- Moves organelles and other particles around within the cell
- Is involved with movements of the cytoplasm called cytoplasmic streaming
- Interacts with extracellular structures, anchoring it in place
What are the three components that make the cytoskeleton?
- Microfilaments
- Intermediate filaments
- microtubules
Microfilaments
Are made up of many linked monomers of a protein called actins
What are the 2 major roles of microfilaments?
- Help the entire cell or parts of a cell to move (pseudopodia = false feet)
- Determine and stabilize cell shape
- cytoplasma streaming = move cytoplasm in a cell
- cytokinesis = cell division
Intermediate filaments
Are the type of cytoskeleton that are diverse and stable, made of multiple strands of fibrous protein wound together.
What are the functions of intermediate filaments?
- They anchor cell structures in place
- maintain nuclear position in cell
- help maintain cell rigidity
Microtubules
are long, hollow, and unbranched cylinders
What are the functions of microtubules?
- Form a rigid internal skeleton for some cells or cell region
- Act as a framework along which motor proteins can move structures within the cell
- Are the main structural component of cilia and flagella
Cilia
are short and usually have many present, move with stiff power stroke and recovery stroke (Basically swimming with multiple legs and arms)
Flagella
Have longer and usually one or two present, undulating movement (can push or pull the cell through its aqueous environment)
Microtubule doublet
They have 9 pairs of fused microtubules on outside and 2 unfused inner microtubules
What are the 3 major roles of the plant cell wall?
- provide rigid support for the cell and limits volume
- Act as a barrier to infection
- Contributes to form during growth and development
