CB1: Key Concepts In Biology Flashcards
What is a eukaryotic cell? Describe it.
A cell with a nucleus. It has a complex structure and can make up whole organisms.
Eg Palisade cells and somatic cells
What is a prokaryotic cell?
A cell with no nucleus. It has a simpler structure than eukaryotes and is unicellular
Eg Bacteria
Name and describe sub cellular structures of a somatic cell
Cell membrane- controls substances entering and leaving the cell
Ribosomes- work in protein synthesis (creating proteins) and translation of genetic material
Mitochondria- where most reactions for respiration happen: transfers energy for cell to work
Cytoplasm- where most chemical reactions happen. Enzymes contained in this gel-like substance aid and control these reactions
Nucleus- contains genetic material arranged into chromosomes and controls cellular activities
Name and describe sub cellular structures of a palisade cell
Ribosomes
Mitochondria
Cell membrane
Nucleus
Cytoplasm
Cell wall- made from cellulose. Maintains cell shape, strengthens it and supports it.
Chloroplasts- contain chlorophyll, a green protein that aids in photosynthesis (where food for the plant is made)
Large vacuole- where cell sap is stored, a weak solution of sugar and salts
Also maintains internal cell pressure which supports cell
How is an egg cell specialised?
Haploid nucleus is able to fuse with a sperm’s haploid nucleus to create a diploid zygote which has the right amount of genetic material
Has nutrients to feed and nourish the embryo or baby at the early stages of life
Has a jelly extracellular coat that provides chemoattractants and hardens once a sperm has fertilised it so more don’t enter
How is a sperm cell specialised?
Sperm have extra long tails to swim to the egg cell and fertilise it
They have haploid nuclei so that they can fuse with an egg cell’s nucleus and create a diploid nucleus for the zygote
There is an acrosome which contains enzymes which breaks down the ovum’s cell membrane and is able to fertilise it
It has many mitochondria in the middle section to provide energy through respiration for the sperm to be able to swim to the ovum
How are ciliated epithelial cells specialised?
Ciliated epithelials have cilia, hair like structures, which beat and move substances along tissue surfaces in one direction
Eg cilia are lined in the airways and waft mucus toward the throat so it can be swallowed and doesn’t go to lungs
How are root hair cells specialised?
They have a large surface area so they can absorb more water for the plant for respiration and photosynthesis
Name and describe features of a prokaryotic cell eg bacteria
Chromosomal DNA- large loop/strand which contains most cellular DNA and controls cell activities and replication
Flagellum- propels the bacterium from harmful substances like toxins and towards nutrients eg water and oxygen
Cell membrane
Ribosomes
Plasmidal DNA- extra loops of DNA. It can contain genes for drug resistance etc
Explain stages of examining a specimen under a light microscope
1) Take a clean slide and use a pipette to put a drop of distilled water on it so the specimen sticks onto it. Use tweezers to put the specimen on the slide.
2) Then stain it. You can use stains to highlight specific sub cellular structures eg methylene blue stains DNA and iodine stains onion cells
3) Place a cover slip over the specimen and press it down gently so no air bubbles appear on it
4) Clip the slide to the stage
5) Choose an objective lens to look through. You can use the coarse adjustment knob to move the stage up or down and the fine adjustment knob to make the image clearer
6) Look through the eyepiece lens to see in the FIELD OF VIEW.
Measure FOV with a clear ruler
It can change if you increase or decrease magnification with the objective lens.
Therefore you need to divide or multiply your field of view by how much the magnification has increased
What is the total magnification?
Total magnification = eyepiece magnification x objective lens magnification
How do you calculate magnification?
Magnification= image size / real size
How do you calculate image size?
Image size = real size x magnification
How do you calculate real size?
Real size = image size / magnification
How do you convert from mm to micrometres to nm to pm?
X1000 each time
How do you convert from pm to nm to micrometres to mm?
/1000 etc
What is an enzyme?
A biological catalyst- it speeds up reactions without changing or running out
Describe the lock and key mechanism
An enzyme has a complementary active site to its substrate and is therefore able to catalyse the reaction
What happens when the temperature/pH is over optimum?
The peptide chains that make up the enzyme unravel and the bonds break
TMT the active site of the enzyme is distorted which means that it is unable to catalyse the reaction and break down its substrate
Stomach enzyme?
Pepsin: optimum pH is 2
What is the use of electron microscopes?
Allow us to see specimens with a higher resolution and a clearer image
What are the quantitative measurements for specimens
Milli 10^-3
Micro 10^-6
Nano 10^-9
Pico 10^-12
What is the affect of substrate concentration on reaction rate?
Rate will go UP as the more substrate, the faster the reactions.
HOWEVER it will plateau as active sites can become saturated with substrate and be full, unable to speed up
Core practical: pH affecting rate of reaction
Fill wells of spotting tile with iodine (to test for starch)
Get Bunsen burner and heat water until it’s 35 degrees
Add 3cm^3 of amylase solution and 1cm^3 of buffer solution with pH5 to a boiling tube
Put boiling tube in water and wait 5 mins
THEN
Add starch solution
Mix and turn on stop clock
Take sample of solution every 10 seconds and put in different well of spotting tile each time
You should see a gradual turning of blue-black iodine back to orangey brown, meaning there is a loss of presence of starch and that amylase has broken it down
How to calculate rate of reaction
Rate= change/time
What breaks down protein and what into?
Protease
Amino acids
What breaks down fats and what into?
Lipase
Fatty acids and glycerol
What breaks down carbohydrates/ starch and what into?
Carbohydrase/amylase
Simple sugars eg maltose
How to test for protein
Biuret test
Add potassium hydroxide
Add copper(II) sulphate
Add test substance
If PURPLE, protein is present
If stays blue- not present
How to test for fats
Emulsion test
Add to ethanol
Shake
Then add to water
If there is a milky precipitate on top, fat is present
Test for starch
Iodine
If present: blue-black
If not: stays orange-brown
Test for SIMPLE SUGARS
Benedict’s reagent
Tests for reducing sugars eg glucose, NOT SUCROSE
Produces coloured precipitate
Higher concentration-> higher up colour scale
Blue-green-yellow-orange-brick red
Calorimetry
Burn dry food under water and measure starting and finishing temperature
Equation for energy in food?
Energy in food= mass of water x water temp change x 4.2
Equation for energy per gram of food?
Energy/gram= energy in food/mass of food
What is diffusion?
The net movement of particles with the concentration gradient from an area of high concentration to an area of low concentration.
Only small molecules can diffuse eg oxygen and amino acids and glucose
Only happens with liquids and gases
What is osmosis
The net movement of WATER MOLECULES through a PARTIALLY PERMEABLE MEMBRANE from a high concentration to low concentration
What is active transport?
The net movement of particles AGAINST THE CONCENTRATION GRADIENT from a LOW to HIGH concentration
Give an example of active transport
Gut gives blood sugar
This is vital for our nourishment and for respiration
Even if gut has LOW CONCENTRATION it still gives blood sugar with HIGH CONCENTRATION in order for us to avoid starving and survive
Osmosis core practical
Potato cubes in increasing concentration of sucrose solution
SHOULD SEE
Potato mass increase in low concentration of sucrose: more water on the outside of potato that inside so water travels from the high-low concentration: potato mass increases
In high concentration of sucrose: potato mass decreases as more water on the inside of potato on outside so water travels from high to low concentration from potato to solution
How to calculate percentage change in mass?
% change in mass= final mass-initial mass/initial mass
