Cells Flashcards
Animal cells
Animal cells are eukaryotic, which means they have a nucleus and other structures which are surrounded by membranes
Cytoplasm
A jelly-like material that contains dissolved nutrients, salts and structures called organelles. It is where many of the chemical reactions happen (in plant, animal and bacterial cells)
Nucleus
A nucleus contains genetic material, including DNA, which controls the cell’s activities (in both plant and animal cells)
Cell membrane
The cell membrane is permeable to some substances, but not to others, and so controls the movement of substances in and out of the cell (in plant, animal and bacterial cells)
Mitochondria
Mitochondria are organelles that contain the enzymes for respiration, and where most energy is released in respiration (in both plant and animal cells)
Ribosomes
Ribosomes are tiny structures where protein synthesis occurs (in both plant and animal cells)
Plant cells
Plant cells are eukaryotic, which means they have a nucleus and other structures which are surrounded by membranes
Chloroplast
An organelle that contains the green pigment - chlorophyll - which absorbs light energy for photosynthesis. It contains the enzymes needed for photosynthesis (only in plant cells)
Cell wall
Plant and bacterial cell walls provide structure and protection. Only plant cell walls are made from cellulose (only in plant and bacterial cells)
Permanent vacuole
Filled with cell sap to help keep the cell swollen (only in plant cells)
(Animal cells may also have vacuoles, but these are small and temporary)
Bacterial cells
Bacteria are all single-celled. The cells are all prokaryotic. This means they do not have a nucleus or any other structures which are surrounded by membranes. They are amongst the simplest of organisms, and their cells do not divide during mitosis. Instead, they copy themselves by binary fission.
Chromosomal DNA
The DNA of bacterial cells is found loose in the cytoplasm and is not contained within a nucleus
Plasmid DNA
Bacteria have small, closed-circles of DNA called plasmids, present in their cytoplasm. Unlike chromosomal DNA, plasmid DNA can move from one bacterium to another giving variation
Flagella
Bacteria can have one or more flagella (singular - flagellum). These can rotate or move in a whip-like motion to move bacterium
Compare the sizes of eukaryotic and prokaryotic cells
Eukaryotic: 5 µm - 100 µm
Prokaryotic: 0.2 µm - 2.0 µm
Compare the outer layers of eukaryotic and prokaryotic cells
Eukaryotic: Cell membrane. Surrounded by cell wall in plants and fungi
Prokaryotic: Cell membrane. Surrounded by cell wall
Compare the cell contents of eukaryotic and prokaryotic cells
Eukaryotic: Cytoplasm. Cell organelles include mitochondria, chloroplasts in plants and ribosomes
Prokaryotic: Cytoplasm. Ribosomes present. There are no mitochondria or chloroplasts
Compare the genetic material of eukaryotic and prokaryotic cells
Eukaryotic: DNA in a nucleus. Plasmids are found in a few simple eukaryotic organisms
Prokaryotic: DNA is a single molecule, found free in the cytoplasm. Additional DNA is found on one or more rings called plasmids
Compare the types of cell division of eukaryotic and prokaryotic cells
Eukaryotic: Mitosis
Prokaryotic: Binary fission
How is a sperm cell adapted to carry out its function?
Head - contains genetic material for fertilisation in a haploid nucleus
Acrosome (in the head) - contains enzymes so sperm can penetrate an egg
Middle piece - contains mitochondria to release energy needed to swim and fertilise egg
Tail - enables sperm to swim
How is an egg cell adapted to carry out its function?
Cytoplasm - contains nutrients for the growth of the early embryo
Haploid nucleus - contains genetic material for fertilisation
Cell membrane - changes after fertilisation by a single sperm so that no more sperm can enter
How is a ciliated epithelial cell adapted to carry out its function?
Cilia on the surface beat to move fluids and particles up the trachea
How do you calculate the magnification of an object?
Magnification = size of image / real size of object
Why do you stain cells before looking at them under a telescope?
Plant cells are usually stained with iodine stain to make the internal structures more visible. Most cells are colourless and stains can be used to add contrast.
However, cheek cells the stain methylene blue can be used to stain the nucleus blue
1 µm = ? nm
1 000 nm
1 m = ? cm
100 cm
1m = ? mm
1 000 mm
1m = ? µm
1 000 000 µm
1m = ? nm
1 000 000 000 nm
