1. Cells Flashcards
What is the function of the cell surface membrane?
Controls substances entering and leaving the cell
Also compartmentalises cells so chemical reactions can take place without interfering with other reactions.
What is the largest organelle in a cell?
Nucleus
What type of membrane surrounds the nucleus?
Double membrane/Nuclear membrane
What is the nuclear envelope?
The structure that surrounds the nucleus
What are chromosomes made up of?
DNA molecules
In what state do chromosomes usually exist?
Loosely coiled state known as chromatin
What is the function of nuclear pores?
Allow materials to pass through the nucleus
What determines amino acid sequences in a protein?
DNA
What does the nucleolus make?
Ribosomes
What are the properties of nucleus?
- Largest organelle
- Double membrane
- Surrounded by nuclear envelope
- Contains chromosomes made uD of DNA molecules
- Chromosomes usually exist in loosely coiled state known as chromatin
- Nuclear pores allow materials to pass through nucleus
- DNA determines amino acid sequences in a protein
- Nucleolus makes ribosomes
What is cytoplasm?
Aqueous material containing organelles
Known as cytosol excluding organelle.
What are ribosomes made of?
Made of rRNA and protein.
Where are ribosomes found?
Found free in cytoplasm and attached to rough endoplasmic reticulum.
What is the size of ribosomes in the cytoplasm?
80s in cytoplasm.
What is the rough endoplasmic reticulum (RER)?
Extensive network of membranes in the cytoplasm enclosing small spaces called cisternae.
How are proteins made on the RER?
Chains of amino acids move into cisternae of RER as they are made.
What happens to cisternae in the RER?
Cisternae then breaks off to vesicles that travel to the Golgi body.
What is the smooth endoplasmic reticulum (SER)?
Less extensive than RER and does not have ribosomes attached to it.
How are cisternae in the SER different from those in the RER?
Cisternae are usually more flattened in RER.
What are the functions of the smooth endoplasmic reticulum?
Synthesis of lipids and steroid hormones; breakdown of toxins.
What is the Golgi body?
Single membrane, close to RER, stack-like membranous sac formed from vesicles of endoplasmic reticulum.
What happens to proteins in the Golgi apparatus?
Proteins are modified here.
What occurs after proteins are modified in the Golgi apparatus?
Vesicles containing modified proteins break away and are transported to cell surface membrane where they are secreted by exocytosis.
Where is the Golgi apparatus mostly found?
Found mostly in metabolically active cells.
What are some roles of the Golgi apparatus?
Synthesis of digest-ive enzymes; formation of lysosome; formation of glycoprotein; transport, modifies and store lipids; secretes carbohydrates.
Properties of RER
- Extensive network of membranes in the cytoplasm
- Encloses small spaces called cisternae
- Proteins are made on the ribosomes
- Chains of amino acids move into cisternae of RER as they are made
- Cisternae then breaks off to vesicles that travel to the Golgi body
Properties of SER
- Less extensive than RER
- Does not have ribosomes attached to it
- Cisternae are usually more flattened than KER
- Synthesis of lipids and steroid hormones
- Breakdown of toxins
Properties of Golgi body
- Stack like membranous sac formed from vesicles of endoplasmic reticulum
- Proteins are modified here
- Vesicles containing modified proteins break away from Golgi apparatus and are transported to cell surface membrane where they are secreted by exocytosis
- Found mostly in metabolically active celis
Roles of Golgi body
- Synthesis of digestive enzymes same
- Formation of lysosome
- Formation of glycoprotein
- Transport, modifies and store lipids
- Secretes carbohydrates
How is the production & release of substances
- Small part of RER pinches off
- Vesicles fuse together
- Form Golgi body
- Proteins are modified in Golgi body
- Vesicles pinches off
- Vesicles move to cell surface membrane
- Chemicals are secreted by exocytosis
Properties of mitochondria
- lum in diameter
- Double membrane organelle
- Inner one is folded to form cristas, larger surface area to volume ratic for more ATP production
- Contains own circular DNA and 70s ribosomes in matrix to produce protein tor enzyme synthesis essential for respiration
- Able to self-replicate
- Where aerobic respiration takes place, ATP is produced
- ATP leaves mitochondrion and spread rapidly to all part of the cell where energy is needed
- Energy is released by breaking the molecule down to ADP and inorganic phosphate by hydrolysis
- ADP can be recycled
Roles of ATP
- Providing energy for active transport
- Providing energy for the synthesis of macromolecules
- Synthesis of organic molecules in light dependent stage of photosynthesis
What is the diameter of mitochondria?
1 micrometer in diameter
What type of membrane does a mitochondrion have?
Double membrane organelle
What is the purpose of the inner membrane’s folding in mitochondria?
To form cristae, providing a larger surface area to volume ratio for more ATP production
What unique genetic material do mitochondria contain?
Own circular DNA
What type of ribosomes are found in the mitochondrial matrix?
70s ribosomes
What is the significance of the proteins produced in the mitochondria?
Essential for enzyme synthesis necessary for respiration
Can mitochondria self-replicate?
Yes
Where does aerobic respiration take place?
In the mitochondria
What is produced during aerobic respiration?
ATP
What happens to ATP after it is produced in the mitochondria?
It leaves the mitochondrion and spreads rapidly to all parts of the cell where energy is needed
How is energy released from ATP?
By breaking the molecule down to ADP and inorganic phosphate by hydrolysis
What can ADP do after energy is released?
Be recycled
What are lysosomes?
Membrane bound packages of hydrolytic enzymes.
Formed from breaking off from Golgi body.
What is the function of lysosomes?
Used to digest bacteria or other cells taken into the cell by phagocytosis or to breakdown damaged organelles within the cell.
What are centrioles?
Structures only found in animal cells made of microtubules arranged in a circular pattern.
How are centrioles arranged?
Two centrioles lie at right angles to one another.
What is the role of centrioles during cell division?
They make spindle fibers.
What are microtubules?
Long, rigid hollow tubes of 25 nm in diameter that make up the cytoskeleton.
What is the function of the cytoskeleton?
Helps to determine cell shape.
What is the cellulose cell wall?
Gives plant cells a definite shape.
What is the function of the cellulose cell wall regarding osmosis?
Prevents the cell from bursting when water enters by osmosis.
What additional strength can the cellulose cell wall have?
Can be reinforced with lignin for extra strength.
What is the permeability of the cellulose cell wall?
Fully permeable, allowing free movement of molecules and ions through the cell surface membrane.
What is the diameter of a chloroplast?
3-10 um
What type of membrane does a chloroplast have?
Double membrane organelle
What is the background material in a chloroplast called?
Stroma
What are the paired membranes in the stroma called?
Thylakoids
What do thylakoid membranes form?
Stacks called grana
What do grana contain that absorbs energy from sunlight?
Chlorophyll
What does a chloroplast manufacture?
ATP
What does a chloroplast contain besides ATP?
Starch grains
What type of DNA does a chloroplast contain?
Own DNA
What type of ribosomes are found in the stroma of a chloroplast?
70s ribosomes
What is the function of the proteins produced by chloroplast ribosomes?
Essential for enzymes involved in photosynthesis
What is a vacuole?
A large permanent central vacuole found in plants.
What surrounds the vacuole?
The vacuole is surrounded by a tonoplast, which controls exchange between the vacuole and cytoplasm.
What does the vacuole contain?
The vacuole contains pigment, enzymes, sugars, other organic compounds, mineral salts, oxygen, and carbon dioxide.
What is the function of the vacuole?
It regulates the osmotic properties of cells.
What are plasmodesmata?
Plasmodesmata are links between plant cells formed by fine strands of cytoplasm.
How is movement through plasmodesmata controlled?
Movement through the pores is thought to be controlled by the structure of the pores.
Properties of Cilia
- Produces rhythmic movement to sweep substances e.g. lung cells to move mucus
- Made up of 9+2 microtubules
What is microvilli
Microscopic cellular membrane protrusion that increases surface area for absorption
Cilia VS Microvilli
Cilia
Longer
Motile mobile
9+2 microtubule
Do not have a role in absorption
Microvilli
Shorter
Immobile
No microtubules
Increases surface area for absorption
Difference between prokaryotic and eurkaryotic cells
Prokaryotic
Smaller (0.5 - 5 um diameter)
No nucleus
No membrane bound organelles
Peptidoglycan cell wall
No mitochondria
Circular DNA
No chloroplast
Contains chloroplast
70s ribosomes
No centricles
Eukaryotic
Bigger (40 um diameter)
Contains nucieus
Contains membrane bound organelles
Cellulose cell wall | No cell wall
Contains mitochondria
Linear DNA associated with histone protein
Contains chloroplast |. No chloroplast
80s ribosomes
No centrioles. |. Contains centrioles
What are viruses?
Non cellular structures
What is the core of a virus made of?
Nucleic acid core (DNA/RNA)
What is a capsid?
A protein shell that encases the viral genome, and some viruses have an outer envelope made of phospholipids
What is the size range of viruses?
20 nm to 300 nm
How do viruses behave in relation to living cells?
Parasitic
How do viruses reproduce?
Only reproduce by infecting and taking over living cells
What does the viral DNA/RNA do in a host cell?
Takes over the protein synthesizing machinery of the host cell to help make new virus particles