C1 (Cytology And Microspy) Flashcards
What are organelles
Parts of cells. Each with specific function
What’s the cell ultrastructure
The organelles and internal structure within organelles
What are the two main types of organisms
Eukaryotic organisms (cells) and prokaryotic organisms (cells).
What organelles do plant cells have that animal cells don’t
Permanent vacuole
Cell wall
Chloroplast
Plasmodesmata
Plasma membrane
Membrane found on surface of animal cells and just inside cell wall plant cells and prokaryotic cells
Mainly made of lipids and protein
Plasma membrane function
Regulates movement substances into and out of the cell
Has receptor molecules, which allow it to respond to chemicals (like hormones)
Cell wall
A rigid structure that surrounds plant cells
Made mainly of the carbohydrate cellulose
Cell wall function
Supports plant cells
Nucleus
Large organelle surrounded by a nuclear envelope (double membrane) which contains many pores
The nucleus contains chromatin (made of DNA and proteins) and often a structure called nucleolus
Nucleus function
It controls cell’s activity (by controlling the transcription of DNA).
DNA contains instructions to make proteins.
The pores allow substances (RNA) to move between nucleus and cytoplasm
Nucleolus makes ribosomes
Lysosomes
A round organelle surrounded by a membrane, with no clear internal structure
Lysosomes function
Contain digestive enzymes, kept separate from cytoplasm by surrounding membrane
Used to digest invading cells.or break down worn out components of cells
Ribosomes
Very small organelle
Either free floats in cytoplasm or is attached to rough endoplasmic reticulum
Made out of proteins and RNA
Not surrounded by a membrane
Ribosomes function
Site where protein synthesis takes place (where proteins are made)
Rough endoplasmic reticulum
A system of membranes enclosing a fluid-filled space. The surface is covered with ribosomes
Rough endoplasmic reticulum function
Folds and processes proteins that have been made at the ribosomes
Smooth endoplasmic reticulum
Similar to rough endoplasmic reticulum, but with no ribosomes
Smooth endoplasmic reticulum function
Synthesises and processes lipids
Vesicle
A small fluid-filled sac in cytoplasm by a membrane
Vesicle function
Transports substances in and out of the cell (via plasma membrane) and between organelles.
Some are found in golgi apparatus or the endoplasmic reticulum, while others are formed at the cell surface
Golgi apparatus
A group of fluid filled, membrane- bound, flattened sacs. Vesicles are often seen at the edge of the sacs
Golgi apparatus function
Processes and packages new lipids and proteins
Also makes lysosomes
Mitochondria
Usually oval-shaped
Double membrane, inner one is folded to form structures called cristae
Inside is matrix, contains enzymes involved respiration
Mitochondria function
Site of aerobic respiration, where ATP is produced
They’re found in large numbers in cells that are very active (require a lot of energy).
Chloroplast
Small, flattened structure found in plant cells
Surrounded double membrane, also had membranes inside (thylakoid membranes) these membranes are stacked up in some parts of the chloroplast to form grana. Grana are linked together by lamellae (thin flat pieces of thylakoid membrane)
Chloroplast function
Site where photosynthesis takes place
Some parts of photosynthesis happen in the grana, and other parts in the stroma (a thick fluid found in chloroplast).
Centrioles
Small, hollow cylinders, made of microtubules (tiny protein cylinders). Found in animal cells, but only some plant cells.
Centrioles function
Involved with the separation of chromosomes during cell division
Cilia
Small, hair like structures found surface membrane so animal cells
Cross section, they have an outer membrane and a ring of nine pairs of proteins microtubules inside, with a single pair in middle
Cilia function
Microtubules allow cilia to move.
Movement used by cell to move substances along cell surface
Flagellum
Flagella on eukaryotic cells like cilia but longer. stick out from cell surface and are surrounded by the plasma membrane.
Inside they’re like cilia too (structure)
Flagellum function
Microtubules contract, make flagellum move.
Flagella used like outboard motors to propel cells forward
Organelles bacteria cells have
Free floating DNA (bacteria chromosomes) Flagellum Plasmids (rings of DNA) Cell wall Plasma membrane Ribosomes
Give differences between prokaryotic and eukaryotic cells (7)
Extremely small / Larger cells
DNA circular / DNA linear
No nucleus (free floating) / Nucleus present
Cell wall made polysaccharide / none for animal, cellulose for plants, chitin for fungi
Few organelles and none membrane bound / many organelles and some membrane bound
Flagella (when present) made protein flagellin, arranged in a helix / when present made microtubules in 9 + 2 formation
Small ribosomes / Larger ribosomes
Give two examples of dyes we can use
Methylene blue
Eosin
In a light microscope why can we see an image
An image is produced because some parts of the object absorb more light than others.
Why do we stain
Sometimes the object being viewed is completely transparent, so use a stain
What’s an eyepiece graticule and how is it used
It’s fitted into the eyepiece, it’s like a transparent ruler with numbers, but no units. So when you look down you will see a scale
What’s stage micrometer and how is it used
Placed on the stage, it’s a microscope slide with accurate scale (has units)
Used to work out the value of the division on the eyepiece graticule at a particular magnification
Resolution
It’s how well a microscope distinguishes between two points that are close together.
Comparing types of microscope
Light microscope, max resolution: 0.2 micrometers, max magnification: x1500
TEM, 0.002 micrometers, can be more than x1000000
SEM, 0.02 micrometers, usually less than x500 000
Electron microscopes
Use electrons to form an image
They have higher resolution than light microscopes and so give more detailed images
TEM
Transmission electron microscopes
They use electromagnetic to focus a beam of electrons, transmitted through specimen to give a 2D image
SEM
Scanning electron microscope
Scan a beam of electrons across the specimen, knocking off electrons from specimen, which is gathered in cathode ray tube to form an image (3D)
Cytoskeleton
Cytoplasms has got a network of protein threads running though it (called the cytoskeleton)
In eukaryotic cells the protein threads arranged as microfilaments (very thin protein strands), and microtubules (tiny protein cylinders)
Cytoskeleton function (4)
Microtubules and microfilaments support cells organelles (keeps them in position)
Help strengthen the cell and maintain its shape
Responsible for transport of organelles and materials within cell
The proteins of the cytoskeleton can cause cell to move
