3.2.1.1 Structure of eukaryotic cells Flashcards
Describe the structure and function of the cell-surface/plasma membrane.
Found on the surface of animal cells and inside the cell wall of other cells.
It is mainly made of protein and lipids - phospholipid bilayer
It regulates the movement of substance into and out of the cell as it is semi-permeable.
It has receptor molecules on it - could respond to chemicals (e.g. hormones)
Describe the structure and function of the nucleus.
Surrounded by a nuclear envelope (double membrane) which makes it easier to regulate what enters and leaves
Nuclear pores found on nuclear envelope allows mRNA and other large molecules out
Contains chromatin which are found in the nucleoplasm
Contains the nucleolus which contains rRNA and is the site of ribosome synthesis
Describe the structure and function of mitochondria.
It has a double membrane - 2 phosolipid bilayers:
Outer membrane controls what leaves and enters,
Inner layer folds into cristae - increases surface area
The inner membrane is the site of ATP production in aerobic respiration as the inner membrane is studded with stalked particles which contain the enzyme ATP synthase
It contains the matrix which is proteinaceous - has many enzymes that are used in the Krebs’ cycle and contains circular DNA + ribosomes (could replicate)
Describe the structure and function of chloroplast.
It has an inner and outer membrane and contains thylakoid membranes inside.
Thylakoid is a single membrane and when stacked, they are called grana
Thylakoid contains chlorophyll which absorbs red and blue light
Grana are linked together by lamellae which are thin, flat pieces of thylakoid membrane
It contains the stroma which is proteinaceous for the Calvin cycle and contains circular DNA + ribosomes, it is the site of light independent reactions
Describe the structure and function of ribosome.
It is made up of a large and small subunit. A groove is present between the subunits to allow RNA to pass through during protein synthesis
They are found free-flowing in the cytoplasm or attached to the rough endoplasmic reticulum
Describe the structure and function of rough endoplasmic reticulum.
It is a system of flattened membrane-bound sacs that are fluid filled - cisternae
Its surface is covered with ribosomes which after protein synthesis, rER folds and process the proteins
Describe the structure and function of smooth endoplasmic reticulum.
It is a system of flattened membrane-bound sacs that are fluid filled - cisternae
It does not have ribosomes on its surface
It is involved in lipids + carbohydrate synthesis, store and transportation
Describe the structure and function of Golgi apparatus.
It is made of a group of cisternae with vesicles found on the edges of sacs
The Golgi apparatus is involved in the modification, processing and packaging of vesicles (e.g. lysosome)
These vesicles are small fluid-filled sacs surrounded by a membrane, they store proteins and lipids made by the Golgi apparatus and transport them out of the cell via the cell membrane
Describe the structure and function of lysosome.
It is a type of Golgi vesicle which is surrounded by a single membrane
They contain digestive, hydrolytic enzymes (e.g. lysozyme)
They are used in phagocytosis and destruction of old cell organelles
Describe the structure and function of the cell wall.
In plants:
The outermost layer is the middle lamella (made of pectin - helps with cell adhesion)
The middle layer is the cell wall. It is made up of cellulose microfibrils and hemicellulose (β-glucose)
The under most layer is the plasma membrane
Fibres are laid down at right-angles to form sheets - have gaps, fully permeable
It is the rigid structure that surrounds cells in plants (cellulose), bacteria (murien) and fungi(chitin)
It is used for structural support and prevents cell lysis (cell membrane popping)
Describe the structure and function of the vacuole.
It is surrounded a single membrane - tonoplast
It contains cell sap - a weak solution of sugar and salts and pigments (e.g. in flower petals)
It helps to maintain pressure inside (osmosis could take place) the cell and keeps the cell rigid. It also prevents plant from wilting
Its involved in the isolation of unwanted chemicals in the cell
