Cell Structure 1.1, 1.2 and 1.3 Flashcards
1.1: Cells are the basic units of life 1.2: Cell biology and microscopy 1.3: Plant and animal cells as seen with a light microscope
Cell definition
The basic unit of all living organisms;
- surrounded by a cell surface membrane
- contains genetic material
- contains cytoplasm containing organelles.
Organelle definition
A functionally and structurally distinct part of a cell, e.g: a ribosome or mitochondrion.
Nucleus definition
A relatively large organelle found in eukaryotic cells but absent from prokaryotic cells; the nucleus contains the cell’s DNA and therefore controls the activities of the cell; it is surrounded by two membranes which together form the nuclear envelope.
Eukaryote definition
An organism whose cells contain a nucleus and other membrane-bound organelles. (Animals, plants, fungi, and some other organisms)
Prokaryote definition
An organism whose cells do not contain a nucleus or any other membrane-bound organelles. (Bacteria)
What did eukaryotes (containing nuclei with DNA surrounded by two membranes) evolve from?
from prokaryotes (no nuclei and DNA free in cytoplasm) more than two billion years ago.
What is the diameter of the smallest structure visible with a human eye?
50-100 μm in diameter.
What are the sizes of the cells in your body?
5-40 μm.
How large is a bacterial cell?
1 μm.
How large is a ribosome?
25 nm.
What fraction of a meter is a millimeter?
one thousandth = 0.001 = 1/1000 = 10^-3
What fraction of a meter is a micrometer?
one millionth = 0.000 001 = 1/1000 000 = 10^–6
What fraction of a meter is a nanometer?
one thousand millionth = 0.000 000 001 =
1/1000 000 000 = 10^–9
Cell surface membrane definition
A very thin membrane (about 7 nm diameter) surrounding all cells; it is partially permeable and controls the exchange of materials between the cell and its environment.
Chromatin definition
The material of which chromosomes are made, consisting of DNA, proteins and small amounts of RNA; visible as patches or fibres within the nucleus when stained. (Mass of coiled threads)
Chromosome definition
In the nucleus of the cells of eukaryotes, a structure made of tightly coiled
chromatin (DNA, proteins and RNA) visible during cell division; the term ‘circular DNA’ is now also commonly used for the circular strand of DNA present in a prokaryotic cell.
Nucleolus definition
A small structure, one or more of which is found inside the nucleus; the nucleolus is usually visible as a densely stained body; its function is to manufacture ribosomes using the information in its own DNA. (Loops of DNA from several chromosomes. 1-5 is common in mammals)
Protoplasm definition
All the living material inside a cell (cytoplasm plus nucleus)
Cytoplasm definition
The contents of a cell, excluding the nucleus. (Aqueous, jelly-like)
Mitochondrion definition
The organelle in eukaryotes in which aerobic respiration takes place.
Photomicrograph definition
A photograph of a specimen as seen with a light microscope.
Why are stains used in light microscopes?
Because many of the cell contents are transparent.
What cell content was discovered by use of stains containing silver and when?
Golgi apparatus/body/complex discovered by Camillo Golgi in 1898.
What does the golgi apparatus do?
It collects and processes molecules within the cell, particularly proteins.
Name 5 similarities between animal and plant cells
- cell surface membrane
- nucleus
- cytoplasm
- mitochondria
- golgi apparatus
Name 4 differences between animal and plant cells
- centrioles
- cell walls and plasmodesmata
- vacuoles
- chloroplasts
Why are plant cells more easily seen under a microscope than animal cells?
They have a cell wall.
What links plant cells to other neighboring cells?
Fine strands of cytoplasm
Cell wall definition
A fully-permeable wall surrounding prokaryote, plant and fungal cells; the wall contains a strengthening material which protects the cell from mechanical damage, supports it (shape) and prevents it from bursting by osmosis if the cell is surrounded by a solution higher than its water potential.
Plasmodesma (Pl. plasmodesmata) definition
A pore-like structure found in plant cell walls; plasmodesmata of neighboring plant cells line up to form tube-like pores through the cell walls, allowing the controlled passage of materials from one cell to the other; the pores contain ER and are lined with the cell surface membrane.
Vacuole definition
A sac-like organelle found in eukaryotic cells; a large, permanent central vacuole is a typical feature of plant cells, where it has a variety of functions including storage of biochemicals such as salts, sugars, and waste products; temporary vacuoles, such as phagocytic vacuoles (also known as phagocytic vesicles) may form in animal cells. Solution of pigments, enzymes, sugars and other organic compounds (incl. waste products) mineral salts, oxygen and carbon dioxide. In plants, vacuoles help to regulate osmotic properties of cells (flow of water inwards and outwards) and pigment of petals of flowers or red pigment of beetroot.
Tonoplast definition
The partially permeable membrane that surrounds plant vacuoles and controls exchange between the vacuole and the cytoplasm.
Chloroplast definition
An organelle, bounded by an envelope (two membranes) in which photosynthesis takes place in eukaryotes.
Photosynthesis definition
The production of organic substances from inorganic ones, using energy from light.
Grana (sing. granum) definition
Stack of membranes inside a chloroplast containing chlorophyll.
