Flashcards in Eukaryotic Cells Deck (40):
What is the cell wall in plants made of?
How does the cell wall become wood?
Impregnanted with lignin
What does pectin do in cell walls?
It holds the cell walls of neighbouring cells together and is formed as part of the middle lamella
What is the difference between a primary and secondary cell wall?
In a primary cell wall all the cells face the same way and it's more flexiable. Secondary walls have more cellulose and are more ridged
What is the plasmodesmata?
Cytoplasmic bridges between cells to allow communication
What is the tonoplast?
A membrane that surrounds the vacuole and controlls what moves in and out
Why is the vacuole important in the cell's water content?
The vacuole is filled with cell sap which means water moves into the cell by osmosis. This keeps the cell turgid once the turgor pressure stabalises and stops the plant from wilting
What are the similarities between chloroplasts and mitochondria?
Have seperate DNA
Have an outer membrane
Folded inner membrane
What are the differences between chloroplasts and mitochondria?
Site of photosynthesis
How is magnification calculated?
Objective lense x magnification of eyepeice lense
What are the advantages of a light microscope?
Can use living tissue
What are the disadvantages of a light microscope?
We have to prepare slides before we view them which may affect what we see
Limited resolution and magnification
How do you use an electron microscope?
Specimin must be dead and placed in a vacume
Electrons bounce off it to form an image
What are the benifits of using an electron microscope?
Huge magnification and resolution
What are the disadvantages of using an electron microscope?
Must be dead first
Hard to prepare slides
What is the function of a cell membrane?
They control what comes in and out of the cell and allows the fluids either side of the cell to have different compositions
What are vesicles?
Membrane sacks that hold the secretions made in cells
What two molocules make up cell membranes?
Lipids and proteins
What kind of lipids are in the membrane?
What structure do the phospoholipids form in the membrane?
How does the proportion of phospholipids containing unsaturated fatty acids affect the fluidity of the membrane?
The more unsaturated fatty acids, the more fluid the membrane
What is the main function of membrane proteins?
To help substances move in and out of the cell.
In what ways can proteins help things move in and out of the cell?
Receptor molocules sensative to specific changes such as hormones
What is the protoplasm?
The cytoplasm and the nucleus combined
Describe the structure of the nucleus
Surrounded by a double nuclear envelope with pores
Contains DNA and proteins
DNA bonded to proteins to form chromatin
What is chromatin?
When DNA is bonded to proteins when the cell is not actively dividing
What is the function of the mitochondria?
To produce ATP for energy
What is the basic structure of a mitochondria?
They have an inner folded membrane and their own DNA
What is the function of the centrioles?
When the cells divide, they pull apart to form spindle that are involved with the movement of chromasomes
What are the two types of ribosome?
Where are 70s ribosomes located?
Mitochondria and chloroplasts
Where are 80s ribosomes located?
What is the rough endoplasmic reticulum?
Covered in 80s ribosomes involved in the production and transport of proteins
What is exocytosis?
Where a vesicle fuses with the cell surface membrane and it's contents are released outside the cell
What is the smooth endoplasmic reticulum?
Has no ribosomes
Involved with transporting steroids and lipids into the cells
What is the golgi apparatus?
A stack of membranes that modify proteins and package them into vesicles for transport
What is a lysosome?
An organelle full of digestive enzymes to break down old organelles or cells
What is a tissue?
A group of specialised cells carrying out a particular function
What is an organ?
A structure made up of several different types of tissues grouped together to carry out a function