cellular structure and function Flashcards
What are the three main ideas of cell theory?
- Everything alive has cells
- Cells arise from preexisting cells - cells beget cells
- Basic unit of life
All cells have what 4 things?
- Cytoplasm
- Ribesomes
- DNA
- Plasma membrane
What is the cell surface to volume ratio?
An increase in surface area allows for more efficient passage of nutrients and wastes in and out of the cell.
And an increase in size is an increase in number of cells
What is the plasma membrane composed of?
It is composed of Phospholipids which are the most abundant lipid in the plasma membrane and they are amphipathic molecules, containing hydrophobic and hydrophilic regions.
what are amphipathic molecules?
molecules that contain hydrophobic and hydrophilic regions.
What does the amphipathic molecules within the plasma membrane create?
It creates a bilayer where the non polar region is inside and the polar heads are outside-
A phospholipid bilayer can exist as a stable boundary between two aqueous compartments.
What does the plasma membrane do?
The plasma membrane is the boundary that separates the living cell from its surroundings. The plasma membrane exhibits selective permeability.
What is selective permeability?
Allows some substances to cross it more easily than others.
What is the Fluid Mosaic Model?
States that a membrane is a fluid structure with a ‘mosaic’ of various proteins embedded in it.
What is a membrane?
a collage of different proteins, often grouped together, embedded in the fluid matrix of the lipid bilayer.
What do proteins do?
determine most of the membranes specific functions
position is important to the function because structure begins function
What are the three types of proteins?
- Peripheral Proteins
- Intergral Proteins
- Transmembrane Proteins
Where are Peripheral Proteins?
they are bound to the surface of the membrane
where are Integral Proteins?
they penetrate the hydrophobic core
where are Transmembrane Proteins
the hydrophobic regions of an intergral protein consists of one or more stretches of non polar amino acids often collies into alpha helixes
What is the role of carbohydrates within the membrane?
cell-cell recognition, cells recognize each other by binding to molecules often containing carbohydrates on the extra cellular surface of plasma membranes
What forms a Glycolipid?
membrane carbohydrates covalently bonded to lipids
What forms Glycoproteins?
membrane carbohydrates covalently bonded to proteins
What determines the asymmetrical distribution of proteins, lipids and associated carbohydrates in the plasma membrane?
The distribution is determined when the membrane is built by the ER and Golgi apparatus (delivery cell) determined by cell behavior.
Why must a cell exchange materials with its surroundings?
Because you need resources - access to outside resources for energy, eating, waste, breathing, ect.
How do things move across the selectively permeable membrane(5 ways)?
- Diffusion
- Osmosis
- Facilitated Transport
- Active Transport
- Endocytosis and Exocytosis
what is Diffusion?
Movement of molecules in space until they hit equilibrium (polar or non polar molecules)
what is Osmosis ?
Specific to one molecule, water!
what is Facilitated Transport?
Does not diffuse across the plasma membrane, facilitated diffusion through an embedded protein. Doesn’t require energy
what is Active Transport?
Transport of molecules across the plasma membrane from lower concentration to higher concentration via a protein carrier which requires energy- uses ATP as energy to power different pumps (opposite direction and same direction)
what is Endocytosis?
transports molecules or cells into the cell via invagination from the plasma membrane to form a vesicle (little piece of membrane acting as a container)
What is a specialized form of Endocytosis?
Phagocytosis- bringing cells into something
what is Exocytosis?
transports molecules outside the cell via fusion of a vesicle with the plasma membrane
What is tonicity?
It refers to the osmotic characteristics of two solutions separated by a selectively permeable membrane. It is commonly used to describe the response of cells in other solutions.
What are the 3 conditions of tonicity?
- Isotonic
- Hypotonic
- Hypertonic
what is Isotonic?
equal amounts of solute inside and outside the cell thus it does not affect the cell
what is Hypotonic?
Less solute than inside the cell- leads to lysis (bursting) because the more water on the outside of the cell it wants to invade the cells -cells will explode
what is Hypertonic?
More solute than inside of the cell leads to the crenation (shriveling) higher concentration of cells - less water - (hyper kid burns more energy-hyperactive leads to shrinking)
What is cytoplasm?
A supportive gel-like substance in the cell which is mostly water with large amounts of ions, amino acids, sugars, and other macromolecules
What is the function of cytoplasm?
To protect and support cells
Where is the region of DNA?
throughout the nucleus
What are Ribosomes?
They are protein factories and complexes made of the ribosomal RNA (ribosomal nucleic acid) and proteins
What is the function of a ribosome?
They carry out protein synthesis in two locations
what two locations to ribosomes carry out protein synthesis?
- In the cytosol (free ribosomes)
2. on the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes)
What is the internal structure of a prokaryotic cell (4 things) :
- No nucleus
- DNA in an unbound region called the nucleoid
- No membrane bound organelles - no internal membranes
- Cytoplasm bound by the plasma membrane
what is the cell wall and capsule is used for?
protection
what is the purpose of Pilus attachments?
connect to other cells and environment around them
Capsule refers to sugars carbohydrates formation of biofilms attachments and exchange of materials diffusion
What is the internal structure of a eukaryotic cell(4 things)
- internal membranes that surrounds and delineates the organelles of the cell (internal membrane that defines organelles)
- Nucleus
- Packaged neatly in the plasma membrane
- Organelles: membrane bound structures with specific functions that compartmentalizes the cell
what is the nucleus?
membrane enclosed region that contains the DNA of the cell
what is a benefit of organelles?
allows for different enzymes this is why theres so much differentiation
each contain its own unique internal conditions
How did the eukaryotic cell come to be?
evidence suggests it arose from archaea- eukaryotic cells and bacteria cells are very chemically distinct and archaea can tolerate very hostile conditions. It doesn’t digest aerobic bacteria because Nucleus can benefit and the bacteria benefits too- mutual symbiosis
cell can make sugar - big cell houses the little cell
What do Mitochondria and Chloroplasts have in common with bacteria (3 things) and what did these similarities lead to?
- developed by a double membrane
- contain free ribosomes and circular DNA molecules
- Grow and reproduce somewhat independently in cells
these similarities led to the endosymbiont theory (internal symbiosis - 2 cells to one functional cell)
What is the purpose of the nucleus?
It is the information center
What do pores do in the nucleus?
They regulate the entry and exit of molecules from the nucleus
How is the shape of the nucleus maintained?
the nuclear size of the envelope is lined with the nuclear lamina which is composed of proteins and maintains the shape the nucleus.
How do proteins act within the nucleus?
the structure of the proteins allows them to function and allow or not to allow passage- it is a rigid gate keeper - controls information (they do a couple of different things-)
Where is the nucleolus located?
It is located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis
process: created in the nucleus - pores allow it to leave- build ribosomes- controlled and regulated in the nucleolus
What are Chromosomes?
The discrete units that DNA are organized into (most condense and compact for)
What is Chromatin?
The combination of DNA and proteins of chromosomes (a little larger than chromosomes)
What does Chromatin do?
it condenses to from discrete chromosomes as a cell prepares to divide (the DNA condenses even further into Chromosomes typically in the chromatin level- neatly packed and controlled)
What is Mitochondria?
It is the power house of the cell and makes ATP. The layering of the membrane gradient of chemical layers is not complete compartments
What is Chloroplast?
Own DNA, own unique ribosomes-makes sugars, photosynthesis-plant cells- outer and inner membrane
What is the central Vacuole?
Holding cells for water- filled with water to keep cells upright and regulates pressure.
What does the Endomembrane System consist of(6 things)?
- Nuclear envelope
- Endoplasmic reticulum (ER)
- Golgi apparatus
- Lysosomes
- Vacuoles
- Plasma membrane
How many classes of ER are there and what are there names?
there are two classes
- Rough ER
- Smooth ER
What does Rough ER do?
(RER) is laced with ribosomes so it is a protein factory (takes RNA message and convert it to proteins)
what does Smooth ER do?
(SER) is lipid synthesis (phospholipids)
the chemical environment is non polar because lipids are hydrophobic - compartmentalization allows for this
What does the Golgi Apparatus do? and how does it do this?
Packages and distributes materials. The front (receiving end) called Cis face and usually located near ER. Materials arrive at the Cis face in transport vesicles that bud off the ER and exit the trans face where they are discharged in serectory vesicles
What are Lysosomes and what do they do?
Contain unique chemical environment- melts food vacuole - merges slightly acidic environment and helps digest - makes lipids / proteins ect. (contain digestive enzymes - breaks stuff down- important for cellular digestion)
How do Lysosomes help mitochondria when it is not working?
Lysosomes combines with peroxisome (diff type or organelle contain oxidizing thing) and can help it to function.
What is the endomembrane system? (3 things)
- It is a complex and dynamic player in a cells compartmental organization.
- It is also a series of membranes in which molecules are transported in a cell.
- It is able to keep chemical reactions contained
What is metabolism?
It is the sum of chemical reactions taking place in the body
What is the cytoskeleton and what does it do?
It is a network of fibers extending throughout the cytoplasm. It organizes the cell structures and activities anchoring many organelles
Which three types of molecular structures compose the cytoskeleton? and what do they do?
- Microtubules : maintain shape of the cell and act as tracks which organelles move along (its hollow)
- Actin filament : involved in cellular movement
- Intermediate filaments : function differs
What do Cilia and Flagella have in common?
They are both made of microtubules and both used in movement
What are Cilia and Flagella differences?
Cilia are about 20x shorter than flagella. Flagella are usually longer than sperm.
What are microfilaments and what two proteins do they carry?
Microfilaments that function in cellular motility contain the protein myosin in addition to actin (is also a protein fillament) .
What does myosin do?
it pulls actin filaments together (myosin motors in muscle cell contraction)
What do actin and myosin do for amoeboid movement?
localized contraction brought about by actin and myosin droves this movement
How do cells crawl?
They crawl along by a surface by extending pseudopodia (cellular extension) and moving toward them.
What is tissue?
collection of cells with the same shape (structure) and same function
What are the 3 main types of cellular junctions?
- Anchoring Junctions
- Tight Junctions
- Gap Junctions
what is a Anchoring Junctions?
Mechanically attach adjacent cells - connects the cytoskeletons of neighboring cells -common in skin cells and heart
what is a Tight Junctions?
(zip block bag) connects the plasma membrane proteins of neighboring cells which produces a zipper like barrier- it holds liquids - produces a barrier- helps seal cells - common in digestive system and kidney -aides in fluid containment
what is a Gap Junctions?
Communications portals between cells - channel proteins in the plasma membrane fuse allowing easy movement between adjacent cells - diffusion—migration—contraction
