Cells Flashcards
Cell surface membrane
Double layer of lipids and proteins
Surrounds cell separating cytoplasm from surrounding environment
Mitochondria
Double bound membrane
Site of cellular respiration
Chloroplast
Site of photosynthesis in plant cells
Golgi apparatus
Responsible for transporting, modifying and packaging proteins and lipids
Lysosomes
Breaks down molecules using enzymes
Ribosome
Responsible for protein synthesis
Rough ER
Protein production, protein folding
Studded with ribosomes
Smooth ER
Production of cellular products like hormones and lipids
Cell vacuole
Membrane bound structures
Filled with water, inorganic and organic molecules to support organelle
Differences with prokaryotic and eukaryotic DNA
Prokaryotic -
circular dna
How do B lymphocytes respond when they are stimulated by antigens
Activated by T cells
Divide by mitosis
To form memory cells and plasma cells
Plasma cells secrete antibodies
What is an antigen
A large foreign molecule that stimulates an immune response
How are number of chromosomes halved in meiosis
Homologous chromosomes
One of each goes to each pole
Describe process of crossing over
Homologous pairs of chromosomes form a bivalent
Chiasma form
Alleles exchanged
New combinations of alleles produced
How would chloroplasts be obtained from leaf tissue
Break tissues in cells
Centrifuge
At different speeds until chloroplasts obtained
How to use cell centrifugation
Cell homogenisation Filter to remove debris Use isotonic solution to prevent damage to cells Keep cold to prevent damage to enzymes Centrifuge to separate cell fragments Respin
Principles of electron transmission microscope
Electrons pass through
Denser parts absorb more electrons
Denser parts appear darker
Electrons have short wavelength so give high resolution
Why must cells be taken from root tip to view mitosis?
This is the region where mitosis takes place
Why must you firmly squash the root tip to view mitosis?
To achieve one layer of cells so light can pass through, allowing it to be viewed on a microscope
How do bacteria replicate?
Binary fission
Replication of DNA
Division of cytoplasm to produce 2 daughter cells
Each with a single copy of circular DNA
What is a membrane formed from?
Phospholipids and proteins
What are glycoproteins formed from?
Carbohydrates bound to proteins
What is the fluid mosaic model?
The Fluid Mosaic Model states that membranes are composed of a Phospholipid Bilayer with various protein molecules floating around within it
What links phospholipid molecules in the membrane?
Cholesterol
Why do cells become more permeable at high temperatures?
The fatty acid tails of the phospholipid bilayer can become more fluid, allowing more movement
Name 3 organelles that are membrane bound
Nucleus, vacuole, lysosomes
What does a cell wall of a plant contain?
Meurin - a glycoprotein
