Topic 2: Cell Structure & Eukaryotic Cells Flashcards
Define Organelle
A structure within a cell that has a specific function
They are membrane bound organelles so have their own membrane
Give 3 examples of organelles
Nucleus
Mitochondria
Golgi Apparatus
Define Cell
Basic unit from which living organisms are built
Describe the make up of a cell
A mass of cytoplasm, containing organelles and is surrounded by a cell membrane
Give 4 examples of different cells
Nerve cell
Blood cell
Root hair cell
Palisade cell
Define Eukaryotic cell
A cell with a distinct nucleus with a nuclear envelope and chromosomes
It contains membrane bound organelles
Give 2 examples of Eukaryotic cells
Plant and animal cells
How are algae different from other types of cells?
Most algae photosynthesise but don’t have many of the distinct cells and tissues found in plants e.g. stomata, xylem and phloem
Algal cells may contain one large chloroplast or several smaller ones
Give 3 differences between plant cells and animal cells
Plant cells have a cellulose cell wall, chloroplasts and a vacuole
Animal cells dont have a cell wall or chloroplasts, but some do have smaller vacuoles
Describe the structure of the Cell surface Membrane (4)
-found around the outside of a cell
- made of proteins embedded in a phospholipid bilayer
-contains cholesterol
-glycoproteins & glycolipids protrude from the outer surface
What is the function of the cell surface membrane?
It controls the transport of substances in and out of a cell
What is the largest organelle in a eukaryotic cell?
The nucleus
Describe the structure of the nucleus (3)
It has a double plasma membrane- the nuclear envelope- with pores
It contains chromosomes that consist of protein-bound, linear DNA
It has nucleoli which are small spherical regions in the nucleus
What is the function of the nucleus? (3)
It contains DNA which contains the genetic information that the cell needs to control its activities
The pores allow substances like RNA to move between the nuclei and cytoplasm
Nucleoli are thought to make ribosomes
Describe the structure of the mitochondria (3)
It is a sausage shaped organelle
It has a double membrane which forms an outer and folded inner layer which forms the CRISTAE
The fluid like matrix contains the enzymes needed for respiration
What is the function of mitochondria?
To produce ATP via aerobic respiration which provides energy for processes like active transport, protein synthesis and cell division
How is the mitochondria adapted for maximum aerobic respiration?
The Cristae increases the internal surface area for it to happen
In cells that are very active/ require energy, mitochondria are found in large amounts
Describe the structure of the Golgi apparatus (3)
Layers of flattened membranes known as sacs or cisternae
Forms vesicles which are small,round and hollow structures
Vesicles are ‘pinned off’ the cisternae and move round the cell to fuse with the cell membrane for the secretion of molecules
What is the function of the Golgi apparatus?
It processes and packages new lipids and proteins
It also makes lysosomes
What is the function of the Golgi vesicle?
They store lipids and proteins made by the Golgi apparatus and transport them out of the cell via the cell membrane
Lysosomes are a type of what?
Golgi vesicle
Describe the structure of lysosomes?
They are a round organelle with no clear internal structure
They contain digestive enzymes called lysozymes
Where are lysosomes found?
They are numerous in phagocytic white blood cells
What is the function of lysosomes?
Because they contain digestive enzymes, they breakdown or hydrolyse unwanted material e.g. worn out organelles, cells or materials ingested by phagocytic white blood cells
Describe the structure of Ribosomes (4)
They are a very small organelle with no membrane
It is made up of proteins and ribosomal RNA
Consists of 2 subunits
They are larger in eukaryotes(80s) and smaller in prokaryotes (70s)
What is the function of Ribosomes?
Protein synthesis
Where are ribosomes found?
Floating free in the cytoplasm or is attached to the rough endoplasmic reticulum
What is the Rough endoplasmic reticulum?
A system of membranes enclosing a fluid filled space
Describe the structure of the rough endoplasmic reticulum (2)
Has a double membrane
Has ribosomes attached
What is the function of the rough endoplasmic reticulum?
It provides a large surface area for protein synthesis
It folds and processes the proteins made
It transports the proteins
Describe the structure of the smooth endoplasmic reticulum
Has a double membrane
No ribosomes
What is the difference between the rough endoplasmic reticulum and the smooth endoplasmic reticulum?
The SER has no ribosomes like the RER
The SER synthesises,stores and transports lipids and carbohydrates but RER does proteins
What is the function of the Smooth endoplasmic reticulum?
To synthesise, store and transport carbohydrates and lipids
Describe the structure of the cell wall that is found in plants and algae
It contains cellulose
It consists of microfibrils embedded in a matrix
Microfibrils are molecules of the polysaccharide cellulose which are bonded together by hydrogen bonds
What is the function of the cell wall?
To provide mechanical strength to stop the cells from bursting due to the pressure from the entry of water by osmosis
It prevents the cell changing shape
The cell wall in fungi doesnt contain cellulose. What polysaccaride does it consist of?
Chitin
Describe the structure of chloroplasts that are found in plants and algae
They have a double membrane
They have layers of membranes called thylakoids which are called grana when stacked
They contain chlorophyll
The stroma is a fluid filled matrix containing enzymes and starch grains
What is the function of chloroplasts?
To absorb light energy for photosynthesis
Thylakoids increase the internal surface area for the light-dependent reactions of photosynthesis
What is the structure of the vacuole in plant cells?
They are membrane bound organelles
They are filled with cell sap- water containing sugars,amino acids and ions
The surrounding membrane is called a tonoplast
What is the function of the cell vacuole?
To maintain turgor pressure, provides support to leaves and flowers due to that pressure
Separates out unwanted materials from the rest of the cell
