Genes & Body Flashcards
What does recessive mean?
A version of a gene that will only have an effect if the other one is also recessive
What does dominant mean?
A version of a gene that will always have an effect
What is the definition of genotype?
The alleles for certain characteristics that are found in an organism
What is the definition of phenotype?
The characteristics a certain set of alleles causes
What is the definition of homozygous?
If both alleles are the same, the organism is homozygous for that characteristic
What is the definition of hetrozygous?
If both alleles are different, the organism is heterozygous for that characteristic
Where is DNA found?
In the nucleus of a cell
Describe DNA
DNA (inside nucleus) is twisted to form chromosomes
Describe a chromosome
Chromosomes (inside DNA) contain genes that code for different characteristics
How many chromosomes do humans have?
There are 46 - 23 from each parent
How many alleles per gene?
There are always 2 alleles per every gene
Describe the conditions of Cystic Fibrosis
Extra sticky mucus Blocked lungs Reproductive problems Breathing problems Lung infections Digestive problems Recessive disease
Describe the conditions of Sickle Cell Disease
Poor circulation Poor oxygen transport Tired easily Resistant to Malaria Recessive disease
Describe homeostasis
Homeostasis is the maintenance of a constant internal environment, despite changes in the external environment
Give examples of homeostasis
Body temperature Blood glucose regulation Water level Blood salt content Blood pH
What is negative feedback?
The results to up and down but stay roughly constant
Describe the process of ‘vaso constriction’ - keeping warm
- The body acts to reduce heat loss
- Hair erector muscles contract and make hair stand upright
- This traps warm air close to the skin
- Sweat glands stop making sweat
- Blood vessels get narrower, less blood near the surface
- This reduces heat loss by radiation
Describe the process of ‘vaso dilation’ - cooling down
- The body acts to increase heat loss
- Hair erector muscles relax and make hair lie flat against skin
- Less air is trapped near the surface, more heat is lost by radiation
- Sweat glands make sweat
- This evaporates off skin
- Blood vessels widen, more blood near the surface
- This increases heat loss by radiation
Why is controlling body temperature important?
So that your body can function and work properly, for example enzymes need to be at a certain temperature to work
How does the body control temperature?
Brain detects temperature
If it’s higher than 37, your body starts sweating
If it’s lower than 37, your body starts shivering
What is in the central nervous system?
Brain and spinal chord
What is the purpose if a neurone?
To carry electrical messages called impulses
What is the speed of a nerve impulse?
15.8 m/s
Describe the reflex arc
Stimulus > Receptor > Sensory Neuron > Spinal Chord > Synapse > Relay Neuron > Motor Neuron > Effector > Response
What is a synapse?
The point where 2 nerves join - synapses also slow down reactions
What is in a vessicle?
It contains a neuro transmitting substance
What is a reflex?
A way of protecting yourself - reflexes are something you’re born with, they do not involve conscious thought
What happens when your blood glucose level is too high?
Your pancreas makes insulin
Your blood transports the insulin around your body
You liver converts glucose to glycogen
Describe Diabetes Type 1
You are born with it
Your body produces no insulin
What is the treatment for Diabetes Type 1?
Low sugar diet - avoid sugary food
Injections of insulin
Describe Diabetes Type 2
If you eat too much sugary food, your insulin stops working and stops being produced - if you are obese, you have a greater chance if getting diabetes
What is the role of insulin?
It lowers your body’s blood sugar level
What is BMI and how do you work it out?
Body Mass Index
height (m2)
Why do diabetics inject insulin about half an hour before each meal?
Because it takes time for the insulin to travel around the body
