Chapter 1: Cell structure Flashcards
How large is a bacterium?
1 to 10 micrometers long
What is a plasmid?
A small ring of free-floating DNA found in prokaryotic cells (cells without a nucleus such as bacteria)
What is cytoplasm?
Cell fluid (mostly water). Reactions happen here
What is a cell wall?
A wall that provides support for the cell, found in bacteria, plants (made of cellulose) and fungi
What is the cell membrane?
The membrane surrounding the cell that controls what substances go in and out of a cell. It also has internal extensions with enzymes attached to them, where respiration occurs
What are ribosomes?
Protein factories, which are suspended in the cytoplasm
What is diffusion?
Net movement of particles from an area of high concentration to an area of lower concentration
What are mitochondria?
Small organelles found in the cytoplasm of eukaryotic cells where respiration takes place
What is a nucleus?
An organelle found in eukaryotic cells where chromosomes are located
What are chromosomes?
Structures containing DNA
What are chloroplasts?
Components of plant cells where light is absorbed and photosynthesis takes place
What is the vacuole?
The area in the middle of a plant cell full of sap, which keeps the cell turgid
How are sperm cells adapted to their purpose?
Their tails and large numbers of mitochondria help them swim,
How are nerve cells adapted to their purpose?
The myelin sheath insulates the electrical impulse, speeding up the electrical impulse. The many long extensions form junctions with other cells
How are muscle cells adapted to their function?
They contain large numbers of mitochondria
What are the 3 types of muscle cell?
Skeletal (manual), cardiac and smooth (automatic)
How are root hair cells in plants adapted to their function?
They have a thin extension sticking out into the soil, increasing the surface area for water and mineral absorption
What is a xylem?
A tube formed of dead plant cells joined together through which water flows during transpiration
What is transpiration?
The gradual release of water vapor from leaves to continue the “pull” off water up from the soil
How are xylem cells adapted to their function
Cell walls strengthened with lignin
What are phloem cells?
Living cells that carry sugars made in photosynthesis to all cells of a plant
What is translocation?
Movement of sugars around a plant
How are phloem cells adapted for their purpose?
Fewer organelles, allowing sugars to travel easily, sieve plates
What is cell differentiation?
The process in which generic cells turn into specialised adapted cells (such as muscle cells). This process happens continually in plants but only in the uterus in mammals
How is total magnification calculated?
Magnification of objective lens * magnification of eyepiece lens
Name the lenses in a light microscope
Eyepiece lens: The lens you look through
Objective lens: 3 lenses to choose from
Name the different focuses
Course focus: Quickly moves the stage up and down
Fine focus: Slowly and sensitively moves the stage up and down
How do scanning electron microscopes work?
They fire a small beam of electrons at a thin slice of the specimen. The beam scans across the image slowly. Electrons scatter from the surface of the sample and are detected to make an image
How do scanning electron microscopes work?
They fire a small beam of electrons at a full specimen (not just a thin slice). The beam scans across the image slowly. Electrons scatter from the surface of the specimen and are detected to make an image
How do transmission electron microscopes work?
They fire a huge beam of electrons at a thin slice of the specimen and detect the ones that make it through
What is the difference between the images formed by scanning and transmission electron microscopes?
Scanning electron microscopes create 3D-looking images, transmission electron microscopes create images of 2D cross-sections. They both produce monochrome images
What is the difference between light and electron microscopes?
Light microscopes are cheaper and lower resolution
