Cell structure in eukaryotes Flashcards
What is the structure of the nucleus?
An organelle with a nuclear membrane with pores surrounding it with free chromatin and the nucleolus inside of it
What is the function of the nucleus?
Control of cell functions and make ribosomes and store chromatin (unravelled DNA)
What is the structure of the nucleolus?
An organelle inside the nucleus with RNA inside it
What is the function of the nucleolus?
produce rRNA to make ribosomes and hold RNA
What is the structure of the nuclear envelope?
A double membrane round the nucleus that has pores
What is the function of the nuclear envelope?
The pores allow large substances like mRNA to leave the nucleus. Substances like steroid hormones, many come from the cytoplasm through the pores
What is the structure of the rough endoplasmic reticulum?
A group of connected membranes with fluid filled cavities called cisternae that is continuous with the nuclear membrane. It has ribosomes on its surface
What is the function of the rough endoplasmic reticulum?
RER transport proteins through the cisternae to the rest of the cell,
It has a large surface area for ribosomes, which bind amino acids into proteins. Then they are sent to the Golgi apparatus
What is the structure of the smooth endoplasmic reticulum?
A group of connected membranes with fluid filled cavities called cisternae that are continuous with the nuclear membrane.
What is the function of the smooth endoplasmic reticulum?
These have enzymes that catalyse reactions to do with lipid metabolism like: making cholesterol, lipids, phospholipids and steroid hormones.
It is also used in absorbing, transporting and making lipids in the gut.
stores carbs and lipids
What is the structure of the Golgi apparatus?
This is a stack of membrane bound flattened sacs with secretory vesicles that bring materials in and out of the Golgi apparatus
What is the function of the Golgi apparatus?
This changes proteins by adding and/or changing its structure by adding carbs, lipids or folding it.
Vesicles then take the to be stored or to the plasma membrane to be used in the membrane or outside the cell
Cis-golgi face sorts and returns wrongly secreted proteins
Trans-golgi face secrete the vesicles that are filled with proteins to other places in the cell.
It makes lysosomes
It makes lipids
It replenishes the plasma membrane
What is the function of the mitochondria?
Site of ATP production in respiration
where are the mitochondria most commonly found
Site of ATP production in respiration
Abundant in cells where most of the metabolic activity takes place, such as neurones where neurotransmitter is synthesised and released
What is the structure of the chloroplast?
Large organelles, around 4-10 um
Had a double membrane with many flattened membranes called thylakoids
Each stack/pile of thylakoids is called a granum (grana)
The fluid filled matrix is called the stoma
Contains loops of DNA and starch grains
chlorophyll pigement present
What is the function of the chloroplast
Site of photosynthesis, where light is turned into ATP from CO2 and water. Water is split to provide the H+ ions in the granum and create ATP. In the second stage the hydrogen reduced the carbon dioxide to create glucose using ATP
What is the structure of a vacuole?
it is bound by a membrane(tonoplast) and filled with fluid.
What is the purpose of a vacuole?
It stores a solution of water and useful ions and molecules for the plant to use.
It is used to make the plant cell stable and turgid when it is full of water as it pushes against the cell wall.
when all cells are turgid the plant is better supported especially in the not wood plants
only plants have a large permanent vacuole
What is the structure of the lysosome?
A small bag filled with a single membrane
produced from the Golgi apparatus and is filled with strong hydrolytic enzymes.
It is more common in phagocytes as they will digest bacteria e.g macrophage and neutrophils.
What is the function of the sex flagella
they extend between cells in some tissues between special junctions enabling cell signalling
What is the structure of the cilia and flagella
They are projections from the cell covered with cell surface membrane and are made of centrioles which are made of microtubules. The cillia are 9:2 arrangement of microtubules
What is the purpose of the cilia and flagella?
The flagella are used in bacteria to move and are also used in the sperm cell to move.
Cilia are used to waft things away from the nose after being covered with mucus to remove bacteria front he body.
nearly all cells have a cilia to be a receptor for their environment
Which organelles are not membrane-bound?
ribosome, cell wall, centrioles and cytoskeleton
What is the purpose of the ribosome?
They are used to synthesise protein.
The ones floating around are for in cell and the ones on RER are for in cell use
What is the structure of the centrioles?
They are made up of bundles of microtubules perpendicular to each other to form a cylinder.
microtubules made of tubulin
What is the structure of the ribosome?
It os a small spherical organelle 25-30 nannometer diameter
made of ribosomal RNA
Made in the nucleus ad 2 separate subunits that join together in cytoplasm
some on RER some float
What is the purpose of centrioles?
They are used to make the cilia and undupolia/flagella. They will rapidly replicate and line up at the edge of the cell surface membrane to sprout outwards to form the cilia or flagella.
They also are used to make the spindle fibres to pull the chromosome as they replicate to form it which attaches to the chromosome and uses proteins to pull the chromosomes.
Centrioles are usually absent from cells of higher plants and can be found in unicellular green algae
centriole form centromere
What is the structure of the cell wall?
It is made of bundles of cellulose and is on the outer membrane
Fungi have wall but it is made out of chitin
peptidoglycan in prokaryotes
What is the purpose of the cell wall?
it is used to support the cell as the vacuole pushes against it keeping it turgid.
It also is used to keep the entire plants shape and structure and strength
they are permeable to allow ions through
What is the structure of the cytoskeleton?
It is made up of:
microfilaments: they are 7 nm in diameter and are made of protein subunits called actin
intermediate filaments:10nm in diameter
microtubule:made of tubulin subunits and are 18-30nm
motor proteins:These are kinesin, mysein, and dyneins which are molecular motors.They are also enzymes which bind to and hydrolyse ATP to use as energy.
What is the purpose of the microfilaments?
Microfilaments are used for mechanical strength, movement, support and structure of the cell.
What is the purpose of microtubules?
They are used for cell shape and support while also allowing things to move through the cells
they make up the cilia and flagella
they form the track along which motor proteins(kinesin and myesein) move or drag proteins from one part of the cell to the other
they form the spindle fibres to move the chromosomes
What is the purpose of intermediate fibres?
they are made of many proteins and they anchor the nucleus in the centre of the cytoplasm
allow cells to adhere to a basement membrane stabilising tissues
they can extend outside the cell between special junctions to allow for cell to cell signalling and to adhere to a basement membrane stabalising the tissue
What is the function of the cytoskeleton?
It supports the cell and helps maintain its shape
It helps the cilia, flagella and undupolia move the cell
It changes the cell shape in cytokinesis, pseudopodia, phagocytosis, endocytosis, exocytosis and muscle contractions
Helps organelles move and keep them in place
-Helps move mRNA and chromosomes
