Topic 2 Cells And Control Flashcards
What are enzymes?
Enzymes are biological catalysts that control reactions in the body. Each enzyme is specific to its substrate and the activity of enzymes is affected by temperature, substrate concentration and pH.
Amylase- breaks down into sugars and carbohydrates
Lipase- breaks down into fatty acids and lipids
Protease- breaks down into proteins and amino acids
What is calorimetry?
The temperature of the water at the start is measured
The mass of the food sample is measured
The food is set alight
The temperature of the water at the end is measured and the change in temperature is calculated
Getting in and out of cells
Diffusion- high concentration to low concentration of molecules through a partially permeable membrane
Active transport- low concentration to high concentration of molecules through a partially permeable membrane
What is mitosis?
- makes two daughter cells
- makes genetically identical chromosomes in the nucleus to the parent cell
- this means two genetically identical diploid body cells are formed
Stages of mitosis
Interphase- chromosomes become visible, DNA already been copied
Prophase- the nuclear membrane breaks down
Metaphase- chromosomes line up along the middle of the cell
Anaphase- chromosomes pulled to opposite sides of the cell
Telophase- new nuclear membrane forms
Cytokinesis- the cell splits making two identical daughter cells
What is cell growth and differentiation?
After growth cells can then differentiate into specialised cells. Cells divide for growth, repair and asexual reproduction. Cancer cells can also form by mitosis via uncontrollable cell division.
What are stem cells?
Stem cells are cells that can divide to produce many types of cell.
Embryonic stem cells- taken from embryos
Adult stem cells- found in differentiated tissue
Meristems
All of these help to cure many diseases including cancer
What are neurones?
Neurons are specialised cells that carry nervous impulses.
Sensory neurones- Carry impulses to the central nervous system
Motor neurones- carry impulses from the central nervous system to effector organs
Relay neurones- are found only in the central nervous system
Dendrites- collect impulses from receptor cells
Fatty myelin sheath- insulates the neurone
Responding to stimuli
Synapses- the point where two neurones meet is called a synapse. There is a small gap between the neurones. The electrical nerve impulse cannot cross this gap, and the impulse is carried by neurotransmitters.
The reflex arc
Reflex arcs involve only three neurones and impulses pass to and fron the spinal cord. These reflexes help protect us from immediate harm. Reflex arcs:
-immediate
- involuntary
- innate
- invariable
Osmosis in potatoes
Results show that when the solution concentration is very dilute, water enters the potato cells. This is due to osmosis because the solute concentration of the potato cells is greater than the surrounding solution. As the solute concentration of the solution increases above that inside the potato cells, osmosis causes water to be lost from the potato.
How do calculate percentage change in mass in potatoes?
Final mass- initial mass / initial mass x 100%
What are growth and percentile charts?
Growth can be measured by an increase in length or increase in mass
Percentile charts can help to show if a child is growing faster or more slowly than is their normal age
Advantages and disadvantages of using stem cells in medicine
Advantages
Embryo cells can produce any type of cell
All stem cells can replace faulty cells with healthy ones
No embryo gets destroyed
Disadvantages
Stem cells may not stop dividing leading to cancer
Adult stem cells can only produce a few types of cells
