Topic 1 - Key Concepts in Biology Flashcards
Eukaryotes
Organisms that are made up of eukaryotic cells
Prokaryotes
A prokaryotic cell (single-celled organism)
Nucleus
Contains genetic material that controls that activities of the cell
How is genetic material arranged?
Into chromosomes
Cytoplasm
A gel-like substance where most of the chemical reactions happen
What does cytoplasm contain?
Enzymes that control the chemical reactions
Cell membrane
Holds the cell together and controls what goes in and out
Mitochondria
Where the most of the reactions for respiration take place
What does respiration transfer?
Energy that a cell needs to work
Ribosomes
Involved in translation of genetic material in the synthesis of proteins
Cell wall
Supports the cell and strengthens it
What is the cell wall made of?
Cellulose
Large vacuole
Maintains the internal pressure to support the cell
What does the large vacuole contain?
Cell sap, a weak solution of sugar and salts
Chloroplasts
Where photosyntehsis occurs, which mades food for the plant
What green substance do chloroplasts contain?
Chlorophyll
Are bacterial cells smaller or larger than plant/animal cells?
A lot smaller
Chromosomal DNA
Controls the cell’s activities and replication
Where does the chromosomal DNA float?
Freely in the cytoplasm
Plasmid DNA
Small loops of extra DNA that aren’t part of the chromosome
What does plasmid DNA contain?
Genes for things like drug resistance
Does plasmid DNA pass between bacteria?
Yes
Flagellum
A long, hair-like structure that rotates to make the bacerium move
What can flagella be used to move bacteria away from?
Harmful substances like toxins
What can flagella be used to move bacteria towards?
Benefitial things like nutrients or oxygen
What is a specialised cell?
Cells that have a structure which makes them adapted to their function
Steps of fertilisation
- Nucleus of egg cell fuses with nucleus of sperm cell
- Fertilised egg is created
- Develops into an embryo
How many chromosomes are in an egg cell and a sperm cell?
23
True/False: egg cells and sperm cells are haploid
True
How many chromosomes does the resulting cell have after fertilisation?
46
Main functions of an egg cell
To carry the female DNA and nourisht he developing embryo in early stages
Adaptaions of an egg cell
- Contains nutrients in the cytoplasm to feed the embryo
- Has a haploid nucleus
- Straight after frtilisation, its membrane changes structure to stop any more sperm getting in
What does the membrane changing structure after fertilisation make sure of?
The offspring end up with the right amount of DNA
Main function of a sperm cell
To transport the male’s DNA to the female’s egg
Adaptations of a sperm cell
- Has a long tail so it can swim to the egg
- Has lots of mitochondria in the middle section to provide the energy (from respiration) needed to swim this distance
- Has an acrosome at the front of the head
- Contains a haploid nucleus
What does the acrosome store in a sperm cell?
Enzymes needed to digest its way through the membrane of the egg cell
What are cilia?
Hair-like structures on the top surface of the cell
Function of ciliated epithelial cells
Move substances
What do the cilia do?
Beat to move substances in one direction, along the surface of the tissue
When were light microscopes invented?
1590s
How do light microscopes work?
By passing light through the specimen
What do light microscopes let us see?
Things like nuclei and chloroplasts
What can we use light microscopes to study?
Living cells
When were electron microscopes invented?
1930s
What do electron microscopes use instead of light?
Electrons
Electron microscopes have a higher … and … than light microscopes
Magnification and resolution
What is the difference between electron microscopes and light microscopes?
Electron microscopes let us see much smaller things in more detail (like the internal structure of mitochondria and chloroplasts)
What have electron microscopes allowed us to have a much greater understanding of?
How cells work and the role of sub-cellular structures
What is magnification?
How many times bigger the image is
What is the formula for magnification using lens magnification?
total magnification = eyepiece lens magnification x objective lens magnification
What is the formula for magnification using measurements of the image and specimen?
magnification = image size / real size
What is 0.000005 m in standard form?
5 x 10^-6 m
How do you convert picometres to nanometres?
Divide by 1000
How do you convert millimetres to micrometres?
Multiply by 1000
What is the order of units for magnification (smallest to largest)?
Millimetre, micrometre, nanometre, picometre
What are enzymes?
Enzymes are biological catalysts produced by living things
What is a cataylst?
A substance which increased the speed of a reaction, without being changed or used up in the reaction
What do enzymes reduce the need for?
High temperatures
Why do we have enzymes?
To speed up the useful chemical reactions in the body
What is the molecule changed in the enzyme reaction?
The substrate
What is an active site?
The part of the enzyme where substrate molecules bind and a chemical reaction take place
Why do enzymes only work with one substrate?
They have a high specificity because, for the enzyme to work, the substrate has to fit into the active site
What happens when the substrate’s shape doesn’t match the active site’s shape?
The reaction won’t be catalysed
Why is it called the ‘lock and key’ mechanism?
The substrate fits into the enzyme’s active site just like a key fits into a lock
What is a substrate?
The molecules on which enzymes act
How does temperature affect the rate of reaction?
A temperature that is too hot will break some of the bonds holding the enzyme together. This changes the shape of the enzyme’s active site, so the substrate won’t fit anymore. The enzyme is denatured.
What is the optimum temperature (for an enzyme)?
The temperature that the enzyme works best at
