Paper 1

Created by

Isabel

Cards (85)

What is a cell? 
The smallest unit of life that can replicate independently
What does the cell membrane do? 
Controls which substances can pass in and out of the cell
What is a nucleus? 
Contains genetic material/DNA
What is a cytoplasm?
Where chemical reaction takes place
What does a mitochondria do? 
Provides cells with energy they need to function
What is a ribosome?
Site of protein synthesis
What is a cell wall and where is it found?
Supports and structures the cell; found only in plant cells
What is a permanent vacuole and where is it found?
Contains cell sap; found only in plant cells
What is a chloroplast and where is it found?
Site of photosynthesis, containing chlorophyll; found only in plant cells
What is an object?
The real object or sample that you're looking at, e.g. onion cells
What is an image? 
The image that we see when we look down the microscope
How does a light microscope work?
1) Light from the room hits the microscopes mirror and it then reflects upward through the object that's being looked at.
2) It is then passed through an objective lense, then through the eyepiece lense, then into our eyes.
What is the aim of a light microscope?
The lenses spread out the light rays, so the image we see is larger than the actual object
What is magnification? 
How many times larger the image is than the object
What is resolution? 
The shortest distance between two points on an object that can still be distinguished as two separate entities (Shortest distance two objects can be apart without being blurred)
What are the pros and cons of light microscopes?
-They're small
-Easy to use
-Relatively cheap
-Resolution is limited to 0.2 micrometres (anything less will appear blurry and not good enough to study subcellular structures)
What are the pros and cons of electron microscopes?
-They're really big
-Very expensive
-Hard to use
-Use electrons instead of light
-Electrons have a wavelength of 0.1 nanometres (This is 2000x better resolution than light microscopes)
-Can study subcellular structures
What is the cell cycle?
The process at which eukaryotic organisms cells are generated
What are the 3 stages of the cell cycle?
-Growth
-DNA replication and mitosis
-Division (Cytokinesis)
What is a stem cell?
An undifferentiated cell that has not yet been specialised and can divide by mitosis to form more cells
What are the features of adult stem cells?
-Found in the bone marrow
-Can divide by mitosis
-Can only differentiate into different types of blood cells
What are the features of plant stem cells?
-Found in meristems (plant tissues)
-As the plant grows these stem cells differentiate into all the cells and tissues that the plant needs such as phloem cells, xylem cells, palisade cells and root hair cells
-They persist form the plants entire life
Where are meristems found?
-Tips of shoots
-Tips of roots
What are the type of stem cells found in animals?
-Adult stem cells
-Embryonic stem cells
What are specialised cells?
Cells designed to carry out a particular role in the body
What are examples of specialised cells?
-Sperm cells
-Muscle cell
-Nerve cell
-Root hair cell
-Phloem cell
-Xylem cell
What does a sperm cell do?
Delivers genetic material to an egg in order to fertilise it
What are specialised features of a sperm cell?
-Has half the amount of genetic material in its nucleus than a normal adult cell so it can combine with the eggs genetic material to form a normal cells worth
-Has a flagellum (tail) allowing the sperm to swim through the uterus and fallopian tube to reach the egg
-The overall cell is streamlined to help it swim
-Has lots of mitochondria providing energy for swimming
-Has lots of digestive enzymes to break a hole into the egg when the sperm reaches it
What is differentiation? 
The process by which a cell changes to become specialised
What are embryonic stem cells and where can they be found?
Stem cells that can differentiate into any type of specialised cell; found in the early embryo
What are adult stem cells and where can they be found?
Stem cells that can only differentiate into different type of blood cells; found in the bone marrow of people of all ages
How can type 1 diabetes be caused?
Cause from damage to the pancreas cells that normally produce insulin
How can paralysis be caused?
Sometimes caused by damage to nerve cells
How can sickle cell anaemia be caused?
Cause by misshapen red blood cells
What are the steps for embryonic stem cells?
1) Extract embryonic stem cells from early embryos
2) Grow them in a laboratory
3)Stimulate them to differentiate into whichever type of specialised cell that we want
4) Give them to the patient to replace their faulty cells
What are the drawbacks of embryonic stem cells?
-Requires embryonic stem cells which have limited supply as they come from embryos
-Ethical issues regards to using embryos
-Rejection because the embryo and human have different genomes, so the patients immune system may reject the stem cells
What happens if a human body rejects the embryonic stem cells?
The body will destroy the stem cells as they're identified as foreign; the patient can be given medication to suppress their immune system but this doesn't always work and can have side effects
What are the risks using stem cell in medicine?
-Virus transmission
-Tumour development
Describe virus Transmission: 
-If the donor stem cells are infected with virus before they were taken by the scientist or whilst in the lab, then when they're transferred into the patient they'd also transfer that virus which could infect the patient causing more problems
Describe tumour development: 
-Because stem cells divide quickly, there's a chance they could get out of control once they're transplanted into the patient, this could develop into a tumour or even cancer