E1 assesment Flashcards
What is the nucleus?
Controls the activity of the cell
What is the mitochondria?
oval shaped, have double membrane- site of aerobic respiration- produces ATP (energy source)
Endoplasmic reticulum?
system of membranes enclosing a fluid filled space- surface is covered in ribosomes, folds and processes proteins made at the ribosomes.
WHATS THE GOLGI APPARATUS?
fluid filled, membrane bound flattened sacs- processes and packages new lipids& proteins. Also make lysosomes.
Lysosomes?
Contain digestive enzymes called lysozymes, used to digest invading cells or to break down worn out components of the cell.
Formula for magnification?
AIM- actual size= image size divided by real size (height of the object) MAGNIFICATION= size of image divided by size of real object
What is magnification?
How large and image is compared to real life.
What is resolution?
Amount of information that can be seen in the image.
How does the transmission electron microscope work?
A beam of electrons passes through the specimen and its dispersed by the structures there.
Limitations for the transmission electron microscope?
have to view it in a vaccum so cant look at living organisms in it
How does the scanning electron microscope?
Specimen coated in a thin layer of metal and a beam of electrons bounces off the surface onto a photographic plate- allows images to be seen in 3D form.
Limitations to the scanning electron microscope?
Lower resolution images compared to TFMs
Differences between TEM and SEM microscopes?
TFMs specimen has to be thin and its in 2D but SFMs have to be thick specimens and its in 3D
4 stages of mitosis
- prophase
- metaphase
- anaphase
- telophase
What happens in prophase?
the chromosomes condense and shorten in size, tiny bundles of proteins (centrioles) start moving to opposite poles of the cell, forming a network of protein fibres called the spindle.
The nuclear envelope (membrane around the nucleus) breaks down and chromosomes lie free in the cytoplasm.
What happens in metaphase?
the chromosomes ( each with two chromatids) line up in the middle of the cell attaching to the spindle by the centromere.
What happens in anaphase?
In anaphase, the centromeres divide separating the sister chromatids , the spindles then contract pulling the chromatids to opposite poles of the spindle, centromere first. Makes chromatids look like a V-shape.
What happens in telophase?
The chromatids reach opposite poles on the spindle. They then uncoil = long and thin again
Now called chromosomes again
Nuclear envelope forms around each of the chromosomes, so there are now 2 nuclei.
Cytoplasm divide (cytokinesis)= 2 daughter cells identical
