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Cell structure and functions
What are the four essential elements to all living cells?
Plasma membrane
Cytoplasm
Chromosomes
Ribosomes
What is the structure of the plasma membrane?
It is made of a bilayer of phospholipid molecules.
The molecule contains:
a hydrophilic head( polar )
a hydrophobic tail(non-polar)unsaturated+ saturated
What is the function of the plasma membrane?
It controls the flow of substances of the cell. That is essential for maintaining the internal environment.
Where and what does the cytoplasm do?
Itās below the plasma membrane within the cell. It is a fluid that cates and environment for cell processes.
What is the cytosol?
Itās the aqueous part of the cytoplasm where DNA synthesis
What is the cytoskeleton?
Itās a network of fibers throughout the cytoplasm
maintain the cellās shape
organize cellās activity and structure
fixes many organelles
chromosome segregation during cell division
Which domains consists of prokaryotic cells?
Bacteria
Archaea/mue bacteria
Which kingdoms make up the domain eukariya?
Animals
Plants
Fungi
Protista
Bacteria and archaea are ____________ distinct.
Bacteria and archaea are evolutionary distinct
What are some structural organelles present in plant cells but not animal cells?
Chloroplasts
Central vacuole
Cell wall
Plasmodesmata
What is the definition of an organelle?
A structure surrounded by a membrane
Describe the structure of a prokaryotic cell
Rigid cell wall (capsule) made of gycocalyx
Plasma membrane
Use flagella or pills for locomotion
How do bacterial plasmids differ in comparison to other organelles?
They contain an extrachromosomal DNA that replicate independently
What does the plasma membrane contain in prokaryotic cells?
Molecular structures that metabolizes food into energy ( mitochondria in eukaryotes)
What does the cell wall do in prokaryotic cells?
It covers and hides the cell from external organisms
What does the mitochondria do in eukaryotic cells?
Site for cellular respiration/energy production
IT IS AN INDEPENDANT ORGANELLE FROM THE CELL
What are some structural organelles present in animal cells but not plant cells?
Lysosomes
Centrioles
*Flagella
Label the following structures on the drawing:
Nuclear envelope
Nuclear pores
Nucleolus
Chromatin
Rough ER
Ribosomes
What is the nuclear envelope?
It encompasses the nucleus region and made up of two lipid bilayers
What are the nuclear pores?
Itās perforation through the nuclear envelope forming channels that regulate the transport of molecules between nucleus and cytoplasm
What is the nucleolus?
Distinct middle area of the nucleus that assembles ribosomes
What is the nuclear lamina?
Itās a dense fibre network of intermediate filaments
Where is a particularity of the ribosomes?
They are not considered an organelle
What are ribosomes made up of?What is their structure?
rRNA + proteins
They have two subunits:Large subunit (top) and small (bottom)
What is the role of ribosomes?
The site for protein synthesis: by decoding mRNA and forming polypeptide chains
Where are the ribosomes located?
Outside the Rough ER/ on nuclear envelope (bound)
In the cytosol (free)
Where is the site of photosynthesis in plant cells?
Chloroplast: use solar energy to produce food (sugar)
What are peroxisomes?
They are organelles (single membrane) which produce H2O2 to change into H2O. Oxidizes it
What are the two membranes called in the mitochondria?
Smooth outer membrane
Inner membrane (cristae) looks like folds
What is the area called between the two mitochondrial membranes?
Intermembrane space
What is the mitochondrial matrix?
The area within the cristae. It stores energy in the form of H+/ is a surface area for enzymes that synthesize ATP
What are plastids? What are some examples?
They contain pigments
Examples include:
chloroplasts
chromoplasts
leucoplasts
tonoplasts
What is the structure of chloroplasts?
Two membranes
Thylakoids (membrane surrounding grana, Light Rx)
Grana (whole stack)
Granum (one pancake)
Stroma (internal fluids, Dark Rx)
What are the three types of molecular structures in the cytoskeleton?
From largest to thinnest:
Microtubules
Intermediate filaments
Microfilaments/actin filaments
With which element does the cytoskeleton need to interact to produce mobility?
Motor proteins (dynein or myosin etc)
What is the structure of a microtubules?
Hollow tube of 13 alpha beta tubulin dimers
What is the structure of a microfilament?
Two (2 double stranded) actin dimers/deactin
Works with myosin (protein) for muscle movement
What is the structure of intermediate filaments?
Fibers of proteins supercoiled into thick cables
What is the name of the path that cytoplasm travels in?
The cytoplasmic stream which is circular. It speeds the distribution of materials in the cell.
What are three extracellular structures?
Cell wall(plants)
Extracellular matrix ECM(animal)
Intercellular junctions
What is the structure and function of the ECM (only in animal cellsā instead of cell wall)
Itās made up of glycoproteins + macromolecules that sits on top of the plasma membrane.
Itās for:
Support
Adhesion
Movement
Regulation
What are intercellular junctions?
They permit for communication and contact with other cells/structures
What is the form of intercellular junction used in plant cells?
Plasmodesmata: Small pores at the edge of cells
What are functions of the plasmodesmata?
Facilitates transport of small molecules from cell to cell
It is highly regulated
What are the forms of intercellular junctions found in animal cells?
Desmosomes
Tight junctions
Gap junctions
What are intercellular junctions made up of?
They are formed by membrane proteins connected to actin cytoskeleton
What are tight junctions?
Presses membranes together to prevent leakage of fluids
What are desmosomes?
They fasten cells together into strong sheets
sheets on bedābedā-dormirādesmosomes
What are gap junctions?
They provide cytoplasmic channels
Note
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