Topic 1 - Key Concepts Flashcards
What are Ribosomes?
Tiny structures where protein synthesis occurs to create proteins.
What are electron microscopes?
They use electrons rather than light. Have a higher magnification and resolution so they let us see much smaller things in more detail like the internal structure of mitochondria and chloroplasts which has allowed a much greater understanding of how cells work and the role of sub cellular structures.
Describe the Benedict’s test for reducing sugars. (6)
1) Place two spatulas of the food sample into a test tube or 1 cm3 if the sample is liquid. Add about 1 cm3 depth of water to the tube and stir to mix.
2) Add an equal volume of Benedict’s solution and mix.
3) Place the tube in a water bath at about 95°C for a few minutes.
4) Record the colour of the solution.
It turns from blue to green to yellow to orange to brick red. The higher the concentration of reducing sugar, the further along the colour change goes.
How is the egg cell adapted to its function? (3)
Contains nutrients in the cyptoplasm to feed the embryo
Has a haploid nucleus
It membrane changes the structure to stop any more sperm getting in so that the offspring ends up with the right amount of DNA
What is plasmid DNA?
Bacteria also have small, closed-circles of DNA called plasmids present in their cytoplasm. Unlike the chromosomal DNA, plasmid DNA can move from one bacterium to another giving variation.
Why do enzymes have a high specifity for their enzyme?
This is because, fr the enzyme to work, the substrate has to fit into the active site. If the substrate’s shape doesn’t match the active site’s shape, then the reaction won’t be catalysed. This is called the ‘lock and key’ mechanism because the substrate fit into the active site like a key fits in a lock.
What is the difference between eukaryotic and prokaryotic?
Eukaryotic cells are complex and include all animal and plant cells. Prokaryotic cells are smaller and simpler such as bacteria cells.
How does a high/low pH affect an enzyme?
This also interferes with the bonds holding the enzyme together. This changes the shape of the active site and denatures the enzyme. All enzymes have an optimum pH which they work best at which is usually pH 7 but not always.
How do you work out magnification?
Image size/ real size
What is chromosomal DNA?
The DNA of bacterial cells is found loose in the cytoplasm. It is called chromosomal DNA and is not contained within a nucleus.
What is an active site?
Every enzyme has an active site. It is the part where it joins on to its substrate to catalyse the reaction.
Which three factors affect the rate of reaction in enzymes?
- Substrate concentration
- pH
- Temperature
How do you work out rate?
1000/time(secs)= Rate (S^-1)
Describe the relationship between millimetre, micrometre, nanometre and picometre.
A millimetre = 1000 micrometers
A micrometer = 1000 nanometers
A nanometer = 1000 picometer
What happens to the enzyme if the temperature is too high?
This increases the rate of reaction at first but if it gets to hot, the bond holding the enzymes together break. This changes the shape of the enzyme’s active site so the substrate won’t fit anymore. The enzyme is said to be denatured. All enzymes have an optimum temperaure that they work best at.
What is the cell membrane?
It controls the movement of substances in and out of the cell.
What is active transport?
Active transport moves particles from low to higher concentration.