Topic 2A: Eukaryotic Cells and Organelles Flashcards
What are prokaryotic organisms?
Single-celled organisms with no nucleus.
What are eukaryotic organisms?
Multi-cellular organisms, made up of complex - nucleus containing - cells.
What are the differences between an animal and plant cell?
Animal Cell Plant Cell
✖️ Cell Wall ✔️
✖️ Vacuole ✔️
✖️ Chloroplasts ✔️
✔️ Lysosomes ✖️What is the structure of an animal cell?
An often rounded cell containing organelles which are enclosed only in a cell-surface membrane.
What is the structure of a plant cell?
An oblong shaped cell containing organelles (including chloroplasts and vacuoles) which are enclosed in a cell-surface membrane and cell wall made from cellulose.
What is the structure of a fungal cell?
A rounded oblong shaped cell containing organelles (excluding chloroplasts) which are enclosed in a cell-surface membrane and a cell wall made from chitin.
What is the structure of an algal cell?
A rounded cell containing organelles (including large chloroplasts and vacuoles) which are enclosed in a cell-surface membrane and a cell wall made from cellulose.
What is the structure of the cell-surface membrane?
A membrane made of lipids/proteins found on the surface of animal cells, and just inside the cell wall of other cells.
What is the structure of the nucleus?
A large organelle containing chromosomes and nucleolus surrounded by a nuclear envelope containing many pores.
What is the function of the cell-surface membrane?
To regulate the movement of substances in and out of the cell.
What is the function of the nucleus?
To control the cell’s activities and make proteins and ribosomes.
What is the structure of the mitochondria?
An oval shaped structure with a double membrane of which the inner membrane is folded to form cristae. Inside the cristae are the matrix which contain respiratory enzymes.
What is the function of mitochondria?
The site of aerobic respiration.
What is the structure of the chloroplast?
A small structure surrounded by a double membrane. It contains thylakoid membranes which are stacked up to form grana. These grana are linked by lamellae.
What is the function of chloroplasts?
The site of photosynthesis.
What is the structure of the Golgi apparatus?
A group of fluid filled, flattened sacs.
What is the function of the Golgi apparatus?
To process and package new lipids and proteins and to make lysosomes.
What is the structure of a Golgi vesicle?
A small fluid-filled sac surrounded by a membrane which is produced by the Golgi apparatus.
What is the function of a Golgi vesicle?
To store lipids and proteins made by the Golgi apparatus and to transport them out of the cell.
What is the structure of a lysosome?
A round organelle surrounded by a membrane, which is a type of Golgi vesicle.
What is the function of a lysosome?
Contains lysozymes which are used to digest cells or break down worn out components of the cell.
What is the structure of a ribosome?
A small organelle which is made up of proteins and RNA, and is attached to the rough endoplasmic reticulum
What is the function of a ribosome?
The site of protein synthesis.
What is the structure of the rough endoplasmic reticulum?
A system of membranes enclosing a fluid-filled space, covered by ribosomes.
What is the function of the rough endoplasmic reticulum?
To fold and process proteins which have been made by the ribosomes.
What is the structure of a smooth endoplasmic reticulum?
A system of membranes enclosing a fluid filled space.
What is the function of the smooth endoplasmic reticulum?
To synthesise and process lipids.
What is the structure of a cell wall?
A rigid structure made of cellulose (or chitin in fungi) which surrounds cells.
What is the function of a cell wall?
To support cells and prevent them from changing shape.
What is the structure of a vacuole?
A membrane-bound organelle containing cell sap, surrounded by a tonoplast.
What is the function of a vacuole?
To maintain the pressure inside a cell and keep it rigid.
How are epithelial cells adapted?
Microvilli:
Increase the surface area for absorption.
Lots of mitochondria:
Provide energy for the transport of molecules into the cell.
How are red blood cells adapted?
No nucleus:
Allows more room for haemoglobin meaning more oxygen can be carried.
How are sperm cells adapted?
Lots of mitochondria:
Provide large amounts of energy to allow the sperm to propel itself towards the egg.
Flagellum:
Allows the sperm to move towards the egg.
What is a tissue?
A group of specialised cells which work together to carry out a function.
What is an organ?
A group of tissues which work together to carry out a function.
What is an organ system?
A group of organs which work together to carry out a function.
What is the structure of a prokaryotic cell?
A small cell with no nucleus. Instead, the genetic information floats free in the cell in a long, coiled up strand. Flagellum allow the cell to move.
Prokaryotic cell replication: What is the process of binary fission?
1) The DNA and plasmids replicate.
2) The cell then grows and the DNA loops move to opposite poles.
3) The cytoplasm then divides, producing two daughter cells.
What is the process of viral replication?
1) Virus attaches to host cell receptor proteins and releases genetic material into the host cell.
2) This genetic material and proteins are replicated and viral components are assembled.
3) These replicated viruses are released from the host cell.
What is the structure of a virus?
A core of genetic material surrounded by a capsid which has attachment proteins on its surface.
How do you work out magnification?
Magnification = size of image
size of object
What is resolution?
How easily you can distinguish between two points that are close together.
What is an optical (light) microscope?
A microscope which uses light to form an image. They have poor resolution and magnification.
What is an electron microscope?
A microscope which uses electrons to form an image? They have good resolution and magnification.
What is a transmission electron microscope (TEM)?
Use electromagnets to transmit a beam of electrons through a specimen.
✔️ High resolution
✖️ Specimens must be thin
✖️ Specimens must be dead (vacuum)
What is a scanning electron microscope?
A beam of electrons are scanned across the specimen.
✔️ Can be used on thick organisms.
✔️ Gives a 3D image.
✖️ Low resolution.
✖️ Specimens must be dead.
How do you prepare a microscope slide?
1) Pipette a small drop of water onto the slide.
2) Place a thin sample of your specimen onto the water drop.
3) Add a drop of stain.
4) Add a cover slip.
What is the process of cell fractionation?
1) Place tissue in ice cold buffer solution to stop the enzymes from working. Ensure the sample is isotonic to prevent damage to organelles through osmosis, and add a buffer solution to maintain the pH.
2) Use a homogeniser to break open the cells, before filtering the mixture to filter out unbroken cells.
3) Spin the filtrate slowly in a centrifuge to produce a pellet containing the densest organelle (nucleus).
4) Pour off the supernatant and centrifuge the filtrate again at a higher speed to produce a pellet made from a different organelle.
What is the cell cycle?
Interphase:
1) Gap Phase 1 - Cell grows and new organelles/proteins are made.
2) Synthesis - Cell replicates it’s DNA.
3) Gap Phase 2 - Cell continues to grow and more proteins are made.
Mitosis:
4) Mitosis - Cell division occurs.
What is the process of mitosis?
Prophase:
1) Chromosomes condense, centrioles migrate to opposite poles, and spindle fibres begin to form.
2) The nuclear membrane breaks down.
Metaphase:
3) The chromosomes align themselves along the equator and are attached to the spindle fibres at the centromere.
Anaphase:
4) The centromeres divide and spindle fibres contract, pulling the sister chromatids apart to opposite poles of the cell.
Telophase:
5) The chromatids uncoil and become chromosomes and the cytoplasm divides through cytokinesis.
6) This forms two identical daughter cells.
What is cancer?
A mutation which causes the rapid division of cells, forming a tumour which invaded surrounding tissues.
How is cancer treated?
1) Chemotherapy is used to prevent the synthesis of enzymes needed for DNA replication. Therefore the cell is unable to enter synthesis phase.
2) Radiation is used to damage DNA, causing the cell to kill itself and preventing further tumour growth.
