CB1, CB2: Key Concepts & Cells Flashcards
What organelles are found in animal cells, and what are their functions?
- Ribosomes (synthesise proteins)
- cell membrane (controls what enters and exits the cell)
- cytoplasm (where chemical reactions take place)
- nucleus (controls the cell and contains DNA)
- mitochondria (where aerobic respiration takes place)
What organelles are found in plant cells, and what are their functions?
- Nucleus (controls the cell and contains DNA)
- cellulose cell wall (provides strength and support
- cell membrane (controls what enters and exits the cell)
- cytoplasm (where chemical reactions take place)
- chloroplasts (where photosynthesis takes place)
- permanent vacuole (cell sap storage)
- mitochondria (where aerobic respiration takes place)
- ribosomes (synthesise proteins)
Total magnification = ?
eyepiece lens * objective lens
magnification
the process of enlarging an image
What is the resolution?
the ability to distinguish between two points
Image size = ?
actual size * total magnification
How is a sperm cell specialised?
- streamlined shape - easier to swim
- acrosome - contains special enzymes to penetrate the egg
- midpiece - contains mitochondria to release lots of energy
- haploid nucleus
- tail - it can swim
How is an egg cell specialised?
- contains nutrients for an embryo in the cytoplasm
- its cell membrane becomes strong once it has been fertilised so that it cannot be fertilised twice
How is a ciliated epithelial cell specialised?
- the cells have many cilia (little hairs) to sweep mucus along the trachea
What’s the difference between eukaryotic cells and prokaryotic cells?
Prokaryotic cells have no membrane-bound organelles (eg: nucleus, mitochondria, chloroplasts)
What are the features of a bacterial cell?
- prokaryotic
- flagellum enables it to swim
- plasma membrane
- capsule - often associated with pathogens
- plasmid - small extra bit of DNA which can replicate independantly
- nucleoid - region in the cell containing most of the DNA
- pili - hollow hair-like appendages which allow it to attach to other cells
What does a salivary gland do?
produces saliva, which contains enzymes
oesophagus
carries food from the mouth to the stomach
liver
breaks down fats and old blood cells
gallbladder
stores bile
stomach
churns the food
pancreas
produces enzymes
small intestine
absorbs small food particles
large intestine
absorbs excess water into the body
rectum
stores waste before it exits
anus
the way out
physical digestion
breaking large pieces of food into small pieces of food (eg: stomach churning food)
chemical digestion
breaking down large molecules (eg: starch) into small molecules (eg: glucose). Requires enzymes - biological catalysts
protease
breaks protein down into amino acids
lipase
breaks lipids (fats) down into fatty acids and glycerol
amylase
breaks down starch into glucose
bile
emulsifies fats
enzymes are…
biological catalysts
enzymes are sensitive to…
pH and high temperature
Lock and key model
The substrate fits into the active site because it is specific and has a complementary shape.
Diffusion
moving a substance from an area of high concentration to an area of low concentration (along the concentration gradient)
Osmosis
diffusion of water across a semi-permiable membrane. Affected by the presence of salt.
Active transport
movement of ions against the concentration gradient.
concentration gradient
moving from an area with high concentration to an area with low concentration
Fick’s law
rate of diffusion = (concentration gradient * SA)/membrane thickness
diploid cell
a cell with two of every chromosome
haploid cell
a cell with half the number of chromosomes
What does mitosis produce?
two genetically identical daughter cells
Why does mitosis take place?
Cells need to divide for growth and repair
What process creates more sperm and egg cells?
Meiosis
What is the cell cycle?
- Growth
- DNA synthesis: DNA replicates to form two copies of each chromosome
- Mitosis
How does asexual reproduction work?
It uses mitosis
What are the phases of mitosis?
(I)PMATC
- Interphase
- prophase
- metaphase
- anaphase
- telephase (cytokenesis)
Interphase is…
when each chromosome is copied
prophase is…
when the nucleus gets dismantled
metaphase is…
when the chromosomes line up in the centre
anaphase is…
when the chromosomes seperate
telephase/cytokenesis is…
How are plant cells different?
The chromosomes reach the poles in telophase.
The cells seperate in cytokenesis - plants don’t do this
Why is there controversy around stem cells?
- Some Christians are against embryonic stem cell use because they believe life begins at conception
Where are stem cells found?
In plants: meristems
In humans/animals: embryos, (can also be found in most parts of the body, but can only specialise into the surrounding tissue)
Why are embryonic stem cells really useful?
They can specialise into anything
Explain growth percentiles
20th percentile: lowest 20%
80th percentile: lowest 80%/top 20%
50th percentile: completely average; lowest 50%, highest 50%
reflex actions
automatic actions that don’t require conscious thought
cerebral cortex
The largest part of the brain. Made of hemispheres. Covered by grey matter called cerebral which is important for intelligence.
* language
* memory
* thought
* reason
* learning
*consciousness
cerebellum
The second largest part of the brain. Rear lower part of the brain. Impulses for coordinated movement.
* balance
* movement coordination
* vision
* posture
medulla oblongata
Connects brain stem to the brain. Controls coughing, sneezing, swallowing, and hiccuping. Vital for essential bodily functions.
* heartbeat
* breathing
* vomiting
* maintaining blood pressure
Pros and cons of CT scans
Machine using X-rays from multiple angles to create a cross-section.
* only scans tissues and organs
* can damage DNA
* dye used can cause kidney problems
Pros and cons of PET scans
Patient ingests radioactive glucose. The machine detects photons emmitted by this.
* can show what is working and what is not
* helps check for cancer
* checks for abnormalities
* radiation exposure
Spinal cord damage treatment
Surgery:
* remove fluid or tissue that presses on the spinal cord
* remove bone fragments, disc fragments, or foreign objects
* fuse broken bones
* place spinal braces
What are neurones also known as?
nerves
sensory neurone
from sensory receptor to brain and spinal cord.
the “input”
synapse
the functional gap between neurones
motor neurones
from brain and spine to muscles and glands
the “output”
intermediate neurones
carry information between neurones - only found in the brain or in the spinal cord
What is the reflex arc?
Stimulus -> Receptor -> Sensory neurone -> Central nervous system (CNS) -> Motor neurone -> Effector -> Response
What is the formula for average speed?
Speed = distance/time
Why are reflexes faster?
There’s a shorter distance.
S=D/T
How does the mammalian eye get light into impulses?
Photoreceptors function as transducers in converting the energy of light stimuli into the code of the nervous impulse.
transducer
turns energy from one form to another
What are the two kinds of photoreceptors in the mammalian eye?
Rods and cones
What are rods for?
“Night vision”
What are cones for?
“Colour vision”
cornea
protective layer over the pupil
pupil
hole which lets in light
sclera
stops too much light getting in
iris
expands or contracts the pupil - changes the APERTURE
Why is the back of the eye black?
It absorbs colour
Why is the sclera white?
otherwise it would let in too much light
When there is bright light, what size does the pupil become and why?
Small to lower the amount of light reaching the photoreceptors
When there is low light, what size does the pupil become and why?
Large to increase the amount of light reaching the photoreceptors
What shape is the lens in the eye? What does it try to do?
Biconvex (converging)
Focusses light onto the fovea centralis
What does a thin lens do?
Bends light less, and causes longsightedness
What does a fat lens do?
Bends light more, and causes shortsightedness
circular muscles…
radial muscles…
circular muscles - contract during pupil constriction, and relax during dilation
radial muscles - contract in dilation, and relax in constriction
