Key Concepts in Biology Flashcards
What cells are eukaryotic
Animal and plant cells
What do eukaryotic cells have
Cell membrane, cytoplasm, and a nucleus containing DNA
What cells are prokaryotic
Bacteria cells
What do prokaryotic cells have
Cell wall, cell membrane, cytoplasm, single circular strand of DNA and plasmids
What are cell structures (e.g., cell wall) examples of
organelles
What are organelles
structures in a cell that have different functions
What is the function of the nucleus (in animal and plant cells)
contains DNA coding for a particular protein needed to build new cells (enclosed in a nuclear membrane)
What is the function of the cytoplasm (in animal and plant cells)
- Liquid substance where chemical reactions occur.
- Contains enzymes.
- Organelles are found in it
What is the function of the cell membrane (in animal and plant cells)
Controls what enters and leaves the cell
What is the function of the mitochondria (in animal and plant cells)
Where aerobic respiration reactions occur, providing energy for the cell
What is the function of the ribosomes (in animal and plant cells)
- Where protein synthesis occurs.
- Found on a structure called the rough endoplasmic reticulum
What is the function of the chloroplasts (in a plant cell)
- Where photosynthesis takes place, providing food for the plant.
- Contains chlorophyll pigment which harvests the light needed for photosynthesis
What is the function of the permanent vacuole (in a plant cell)
- Contains cell sap
- Found within the cytoplasm
- Improves cell’s rigidity
What is the function of the cell wall (in a plant cell)
- Made from cellulose
- Provides strength to the cell
What is the function of the cell wall (in a bacteria cell)
It’s made of a different compound (peptidoglycan)
What is the function of the chromosomal DNA (in bacteria cells)
As bacteria cells have no nucleus, this floats in the cytoplasm
What is the function of the plasmids (in bacteria cells)
Small rings of DNA - code for extra genes to those provided by chromosomal DNA
What is the function of the flagella (in bacteria cells)
Long, thin, ‘whip-like’ tails attached to bacteria that allow them to move
How do cells specialise
Through the process of differentiation
What is differentiation
a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role
When can cells differentiate
once, early on
What are stem cells
Cells that have the ability to differentiate their whole life
3 examples of specialised cells in animals
- Sperm cells
- Egg cells
- Ciliated epithelial cells
What is a sperm cell
A specialised cell that carries the male’s DNA to the egg cell for successful reproduction
Describe a sperm cell
- Streamlined head and long tail to aid swimming
- Many mitochondria (which supply energy to allow the cell to move)
- The acrosome has digestive enzymes which break down the outer layers of the egg cell’s membrane
- Haploid nucleus
What is an egg cell
A specialised cell that accepts a single sperm cell and develops into an embryo
Describe an egg cell
- Surrounded by a special cell membrane (only accepts one sperm cell)
- Lots of mitochondria to provide an energy source for the developing embryo
- Large size and cytoplasm to allow quick, repeated division as the embryo grows
What is a ciliated epithelial cell
A specialised cell that wafts bacteria to the stomach
Describe a ciliated epithelial cell
- Long, hair-like processes called cilia waft bacteria trapped by sticky mucus down to the stomach
- The bacteria is then killed by the stomach acid.
3 examples of specialised cells in plants
- Root hair cells
- Xylem cells
- Phloem cells
What is a root hair cell
A specialised cell that takes up water (by osmosis) and mineral ions (by active transport) from the soil
Describe a root hair cell
- Large surface area (due to root hairs - meaning more water can move in)
- Large permanent vacuole (affects speed of movement of water from soil to cell)
- Mitochondria provides energy from respiration (for the active transport of mineral ions into the root hair cell)
What is a xylem cell
A specialised cell that transports water and mineral ions up the plant from the roots to the shoots
Describe a xylem cell
- (upon formation), a chemical called lignin is deposited, which causes the cells to die. (they become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through
- Lignin is deposited in spirals which helps the cells withstand the pressure from the movement of water
What is a phloem cell
A specialised cell that carries the products of photosynthesis to all parts of the plants
Describe a phloem cell
- Cell walls form structures called sieve plates when they break down, allowing the movement of substances from cell to cell
- Mitochondria supplies the energy the cells need to be alive
What can you use to see extremely small structures (such as cells)
A microscope
What are the 2 types of microscope
- Light microscope
- Electron microscope
Describe a light microscope
- 2 lenses
- illuminated from underneath
- max magnification = 2000x
- max resolving power = 200nm
- Used to view tissues, cells, and large sub-cellular structures
Describe an electron microscope
- Electrons used to form an image (because electrons have a much smaller wavelength than light waves)
- 2 types: scanning electron microscope (creates 3D images) + transmission electron microscope (creates 2D images)
- Max magnification = 2,000,000x
- Max resolving power = 10nm (SEM)
- Max resolving power = 0.2nm (TEM)
What are transmission electron microscopes used to discover
Viruses - poliovirus, smallpox, ebola
What are electron microscopes used for
examining proteins in much greater detail
Describe the structure of a bacteria cell
- Flagellum
- Slime coat (for protection)
- Flexible cell wall (for support)
- Cell membrane
- Cytoplasm
- Chromosonal DNA
- Plasmids
What are enzymes
Biological catalysts that increase the rate of reactions
What do enzymes do in humans
Turn large molecules in our food into smaller subunits they are made of
Define ‘Synthesis’
Building larger molecules from smaller subunits
Give 2 examples of polymers
- Complex carbohydrates
- Proteins
What are polomers
Made up of many similar small molecules (monomers) joined in a chain
Name 4 different enzymes
- Amylase
- Catalase
- Starch synthase
- DNA polymerase
Where is amylase found
The saliva and small intestine
What reaction does amylase catalyse
Breaking down starch into small sugars - such as maltose
Where is catalse found
Most cells - especially liver cells
What reaction does catalase catalyse
Breaking down hydrogen peroxide to water and oxygen
Where is starch synthase found
Plants
What reaction does starch synthase catalyse
Synthesis of starch from glucose
Where is DNA polymerase found
Nucleus
What reaction does DNA polymerase catalyse
Synthesis of DNA from its monomers
What are chemical reagents for
To facilitate a reaction
What are reducing sugars
All of the smallest sugars
