Flashcards for AQA A Level Biology Chapter 3- Cell Structure
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Course
Chapter 3- Cell Structure
Institution
AQA
Flashcards for A Level biology Chapter 1 Biomolecules. Contain all you need to know for this chapter of the course. Are detailed and concise, and work best with Anki, but can be used with quizlet. They are in the form of a txt document that can be imported into anki or quizlet. Some images are miss...
What is the resolution of a microscope? The minimum distance two objects can be
apart for them to appear as separate items
What are the three qualities of the solution in which cell fractionation is done?
Buffer- maintains pH to prevent damage to important structures<div>Has the
same water potential as the sample- this is to prevent osmotic
damage</div><div>Cold- to prevent enzyme activity and associated damage</div>
What are the two stages of cell fractionation?
Homogenisation<div>Ultracentrifugation </div>
What is the purpose of homogenisation? To break up the cells and release the
organelles into the solution
How does homogenisation work? The cells are put in a blender to break them up. The
<b>homogenate</b> is then filtered to remove large debris and whole cells.
What is the objective of ultracentrifugation? To separate out the organelles in
the homogenate
How does ultracentrifugation work? The homogenate is spun at high speeds so that
the heaviest organelles settle at the bottom as a pellet. The first pellet is made
up of nuclei. The <b>supernatant</b> (not pellet solution) is then spun at a
higher speed to obtain the next heaviest organelle, in this case the mitochondria.
This is repeated until the desired organelles are obtained.
What focusses an electron microscope? Magnets
What are the issues with the staining process for electron microscopes? It is
complex and time consuming<div>It can create artefacts in the image, which can be
misconstrued for organelles</div>
How do you calibrate an eyepiece graticule? You place a stage micrometer next
to the graticule scale, and magnify to the necessary magnification. You then use
the actual measurements on the micrometer to find the value of a graticule
division, allowing you to measure the length of the object in the image.
What is the purpose of the nucleus? It holds genetic material<div>Site of
transcription </div><div>Produces mRNA, tRNA and rRNA</div>
"""What is a mitochondrion's purpose?""" The site of respiration
What is the structure of a mitochondrion? """<img src=""""image-
ce8927b703cb3fce469fbc728c5a6dfe1c35fe43.png"""">"""
What is the purpose of cristae in mitochondria? They provide a larger surface area
for enzymes and proteins involved in respiration to attach to
What is the purpose of the matrix? Holds all of the proteins (incl enzymes),
lipids, ribosomes and DNA needed for respiration
What is the purpose of chloroplasts? The site of photosynthesis
What is the structure of chloroplasts? """<img src=""""image-
141924f0c28da4034e8b4a8fa66984f68e2f0c30.png"""">"""
What are grana? Stacks of thylakoids
What is the purpose of grana? To provide additional surface area for chlorophyll on
the thylakoids
What links grana? Lamellae
What do thylakoids contain? Chlorophyll
What is the stroma? The fluid that contains all of the DNA, ribosomes, proteins
and starch grains necessary for photosynthesis
What is an endoplasmic reticulum? A system of sheet-like membranes that are
distributed throughout the cytoplasm of cells. The membranes enclose a network of
tubules and sacs called cisternae.
What are the two types of ER and what separates them? Rough ER- has ribosomes
attached and can be found close to the nucleus<div>Smooth ER- does not have
ribosomes and can be found throughout the cell</div>
What is the purpose of rough ER? To provide a large surface area for protein
synthesis and to provide a network for the transport of these proteins
What is the purpose of smooth ER? To synthesise, store and transport lipids and
carbohydrates
What is the golgi apparatus? A smaller version of smooth ER- sheets of membranes
that make up cisternae- with vesicles around
What are vesicles? Packages made out of membrane that contain proteins that go
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