Cells Flashcards
What is the structure and function of the membrane?
Structure - phospholipid bilayer, with protein molecules and protein channels integrated within
Function - controls passage of entry of substances in and out of cell, and its the site of cell communication via receptors
What is the structure and function of the nucleus?
Structure - membrane bound organelle, with a nucleolus, nuclear envelope, nuclear pore, nucleoplasm and chromatin
Function - Stores DNA (chromatin), nuclear pore allows mRNA and ribosomes to pass through
What is the structure and function of the mitochondria?
Structure -
Function - carries out aerobic respiration to produce ATP
What is the structure and function of the chloroplast?
Structure - Double membrane bound which contains fluid sacs called thylakoids, each thylakoid is joined by a lamella and each stack of thylakoid is called a
granum

Function -site of photosynthesis
What is the structure and function of the Golgi apparatus?
Structure - Stack of curved membranes containing lumen and two faces (cis face and trans face)
Function - Modifies proteins,
Sorts packages and transport molecules around the cell
What is the structure and function of the lysosomes?
Structure - Small round membrane vesicles formed by Golgi bodies
Function - Contains digestive enzymes to break down pathogens,old organelles,cells and food molecules
What is the structure and function of the ribosomes?
Consists of two separate RNA-proteins
Protein synthesis
What is the structure and function of the rough endoplasmic reticulum?
Series of convoluted,flattened sheets
Provides a larger surface area for protein synthesis
What is the structure and function of the smooth endoplasmnic reticulum?
Tue like structures located around the RER
Synthesises, stores and transports lipids and carbohydrates
What is the structure and function of the vacuole?
Thin membrane filled with fluid
Maintains water potential and keeps the cell turgid
Explain the differences between eukaryotic and prokaryotic cells
Eukaryotic cells have a nucleus containing the DNA whereas prokaryotic cells have free-floating DNA
DNA is linear and associated with histone proteins in eukaryotic cells and DNA is circular and not associated with histone proteins in prokaryotic cells
Eukaryotic have larger ribosomes prokaryotic have smaller ribosomes
Prokaryotic cells may have additional organelles e.g. flagellum and capsule (etc.)
Explain the structure and function of virus cells
Structure - Cellular non-living cell
Nucleic acid core and a protein coat called a ‘capsid’
Function -  replicated by binding to the host cell and injecting their genetic material into the cell using the hosts machinery to replicate and burst out of the host cell
Describe optical microscopes
Use light to form an image
Results in low resolution (200nm max)
Cannot be used to observe smaller organelles e.g. ribosomes, endoplasmic reticulum or lysosomes
Maximum magnification is up to ×1500
Describe electron microscopes
Use electrons to form an image
Increased resolution end result in a more detailed image (0.2nm max)
Maximum magnification of up to x1,500,000
There are two types of electron microscopes:
Transmission electron microscopes (TEMs)
Scanning electron microscope (SEMs)

State the difference between magnification and resolution
Magnification - how much bigger the image is in comparison to the original object viewed by the naked eye
Resolution - how about a microscope distinguishes between two points that are close together
Magnification is how big an image is and resolution is how clear an image is
List the steps of ultracentrifugation
1- Homogenation: cells are blended in a homogeniser forming a homogenate which is then placed into a centrifuge
2-  Filtration: Homogenate is filtered to remove any large bits or debris
3- Ultracentrifugation: Centrifuge is spun at different speeds with separates organelles into sediment or pellets
In what stage does DNA replication take place?
S phase
Define mitosis
A process of nuclear division by which two genetically identical daughter cells are produced from the parent cell
How are tumors formed?
Formed from cancer cells
Tutors are formed from uncontrolled cell division
What is the main aim of cancer treatments?
Explain the stages of binary fission
• Cell replicates it’s DNA
• Cytoplasmic membrane elongates separating DNA molecules
•A cross wall forms; and membrane splits /turns inside out
• Cross wall forms completely
• Two daughter cells are formed
Describe the basic structure of a cell membrane
(Use a diagram)
A bilayer consisting of phospholipids integrated with protein channels
Describe the structure of a phospholipid
Phospholipid head is composed of a phosphate group and a glycerol, this is hydrophilic which means it’s attracted to water.
Phospholipid tale is composed of two fatty acids, this is hydrophobic which means it repels water.
Describe the fluid mosaic model of membranes
Fluid mosaic model is a cell membrane that acts as a barrier and controls what passes in and out of the cell. It consists of organelles like phospholipids, proteins, glycoproteins, glycolipids and cholesterol
Explain the role of cholesterol in the membrane
Cholesterol adds rigidity to the cell which reduces lateral movement
Explain the role of glycolipids in the cell membrane
Glycolipids are cell-surface receptors which allow cells to adhere and form tissues
Explain the function of extrinsic and intrinsic proteins in the cell membrane
List three factors that affect membrane permeability
How does temperature affect membrane permeability?
How does pH affect membrane permeability?
How does the use of a solvent affect membrane permeability?
List the five ways molecules move through a membrane
Diffusion
Facilitated diffusion
Co-transport
Osmosis
Active transport
Define diffusion
Net movement of particles from an area of high concentration to an area of low concentration
How and what molecules move through the membrane via diffusion?
Define osmosis
Net movement of water molecules from an area of high water potential to the area of low water potential across a partially permeable membrane
What is the difference between simple diffusion and facilitated diffusion?
How and what molecules move through a membrane via facilitated diffusion?
Define active transport
How and what molecules move through the membrane via active transport?
Define co-transport
How and what molecules move through the membrane via co-transport ?
Explain how channel and carrier proteins work
Compare and contrast of active transport and facilitated diffusion 
Compare and contrast transmission electron microscopes and scanning electron microscopes
What is the equation for magnification?
State the conditions needed for cell fractionation and explain the reason behind each
Ice cold - To reduce the activity of enzymes
Isotonic - To produce the same water potential and prevent water from moving into the cell so no expansion occurs
Buffered - Prevent organelle are proteins from being denatured
Name the first stage of mitosis and explain what happens during this phase
-Prophase
•Chromosomes condense and become visible
•Nuclear envelope breaks down
•Centrioles move to opposite poles

Name the second stage of mitosis and explain what happens during this phase
-Metaphase
• Centrioles release spindle fibres
• Spindle fibres attach to centromeres which joins the two chromatids together forming chromosome
•Chromosomes line up at the equator of the cell
Name the third phase of mitosis and explain what happens during this phase
-Anaphase
• Centimetres divide
• Chromatids now move to opposite poles
Name the fourth stage of mitosis and explain what happens during this phase
-Telophase
• Chromosomes uncoil therefore not visible anymore
• nuclear envelope reforms
What happens during cytokinesis in mitosis
 Cell membrane splits forming two identical daughter cells
