Topic 2.1 Eukaryotic cells Flashcards
Define a tissue
a group of specialised cells carrying out a particular bodily function
Define an organ
a structure made up of several different types of tissues grouped together to carry out a particular function for the body
Define an organ system
a group of organs working together to carry out a particular functions in the body
What are epithelial tissues?
tissues that from the lining of surfaces inside and outside the body
What are the 4 main types of tissue in the body?
- epithelial tissue
- muscle tissue
- connective tissue
- nervous tissue
Which type of epithelial cells usually line blood vessel surfaces and the walls of alveoli and capillaries?
squamous epithelium
What is a light microscope?
a tool that uses a beam of light and optical lenses to magnify specimens up to 1500x life size
What is an electron microscope?
a tool that uses a beam of electrons and magnetic lenses to magnify specimens up to 500 000 x life size
Define magnification
a measure of how much bigger the image you see is than the real object
Define resolution
a measure of how close together 2 objects can be before they are seen as one
What is a transmission electron micrograph (TEM)?
micrographs produced by the electron microscope that gives 2D images like those from a light microscope, but magnified up to 500 000 X
What is a scanning electron micrograph (SEM)?
micrographs produced by the electron microscope that have a lower magnification than the TEMs, but produce a 3D image
Give the equation for total magnification
total magnification= magnification of objective lens x magnification of eyepiece lens
State the advantages of a light microscope
- can see living organisms or parts of them, useful as it allows you to compare prepared slides with living tissue
- relatively cheap so available in schools, unis, hospitals and industrial labs and research labs
- light and portable
State the disadvantages of a light microscope
- preservation and staining tissue can produce artefacts in the tissues being observed
- limited powers of resolution and magnification
State the advantages of an electron microscope
-huge powers of magnification + resolution
State the disadvantages of an electron microscope
- all specimens examined in a vacuum so can’t see living material
- specimens undergo treatment resulting in artefacts
- preparation is very skilled work
- extremely expensive
- large and has to be kept under constant temperature and pressure
Define organelles
sub-cellular bodies found in the cytoplasm of cells
Define eukaryotes
a group of organisms with cells that have genetic material contained in a membrane-bound nucleus and also contain a number of membrane-bound organelles such as mitochondria and choloroplasts
What are prokaryotes?
a group of organisms including bacteria that have few organelles and have no nucleus
What is the cell surface membrane?
the membrane that forms the outer boundary of the cytoplasm of a cell and controls the movement of substances into and out of the cell
What are vesicles?
membrane ‘bags’ that hold secretions made in cells
What are polar lipids?
lipids with one end attached to a polar group e.g. phosphate group that makes one end hydrophobic and one hydrophilic
What are gated channels?
protein channels through the lipid bilayer of a membrane that are opened or closed, depending on cell conditions
What is the fluid mosaic model?
the current model of the structure of the cell membrane including floating proteins forming pores, channels and carrier systems in a lipid bilayer
What is the cytoplasm?
a jelly-like liquid that makes up the bulk of the cell and contains the organelles
What is the nucleus?
an organelle containing the nucleic acids, DNA and RNA as well as protein, surrounded by a double nuclear envelope with pores
What is the protoplasm?
the cytoplasm and nucleus combined
What is the ultrastructure?
the detailed organisation of the cell, only visible using an electron microscope
What does intracellular mean?
inside the cell
What is chromatin?
granular combination of DNA bonded to histones found in the nucleus when the cell isn’t actively dividing
What is the nucleolus?
an extra dense area of almost pure DNA and protein found in the nucleus involved in the production of ribosomes and control growth and division
What is the mitochondria?
rod-like structures with inner and outer membranes, site of aerobic respiration
What are cristae?
the infoldings of the mitochondrial inner membrane which provide a large area for respiration reactions
What are eubacteria?
true bacteria, prokaryotic organisms
What is the endosymbiotic theory?
suggests that the mitochondria and the chloroplasts originated as independent prokaryotic organisms that began living symbiotically inside other cells as endosymbionts
What are centrioles?
bundles of tubules found near the nucleus and involved in cell division by the production of a spindle of microtubules that move the spindles to opposite ends of the cell
What is a spindle?
a set of overlapping microtubules running the length of the cell, formed as the centrioles pull apart in mitosis and meiosis
What is the cytoskeleton?
a dynamic, 3D web-like structure made up of microfilaments and microtubules that fill the cytoplasm and gives it structure, keeping the organelles in place and enabling cell movements and transport within the cell
What are microfilaments?
protein fibres that makes up part of the structure of the cytoskeleton
Define a vacuole
a fluid-filled cavity within the cytoplasm of a cell surrounded by a membrane
What are contractile vacuoles?
vacuoles that can fill and empty to help control the concentration of the cytoplasm of simple freshwater animals
Define 80S ribosomes
main type of ribosomes found in eukaryotic cells, consisting of ribosomal RNA and protein in ratio 1:1. made up of a 40S subunit and 60S subunit, site of protein synthesis
Define 70S ribsomes
found in prokaryotes, mitochondria and chloroplasts. consist of ribosomal RNA and protein in the ratio 2:1, site of protein synthesis and transport proteins. made up of 50S and 30S subunits
What is the rough endoplasmic reticulum (RER)?
covered in 80S ribosomes and involved in the synthesis and transport of proteins. large surface area, can transport proteins through exocytosis
What is the smooth endoplasmic reticulum (SER)?
smooth tubular structure with no ribosomes, involved in the synthesis and transport of lipids and steroids
What is exocytosis?
energy-requiring process by which a vesicle fuses with the surface of the membrane so the contents are released to the outside of the cell
What is the golgi apparatus?
stacks of membranes that modify proteins made elsewhere in the cell and package them into vesicles for transport, they also produce materials for plant cell walls and insect cuticles
What’s a lysosome?
an organelle full of digestive enzymes used to break down worn out cells or organelles, or to digest food in simple organisms
Define apoptosis
programme cell death- the breakdown of worn out, damaged or deceased cells by the lysosomes
What is the tonoplast?
the specialised membrane that surrounds the vacuole in plant cells and controls movement into and out of the cell sap
What is cell sap?
aqueous solution that fills the permanent vacuole
What’s osmosis?
the movement of water molecules from a region of high to lower water concentration, down a concentration gradient through a partially permeable membrane
Define a cholroplast
an organelle adapted to carry out photosynthesis, containing chlorophyll (green pigment)
What is cholophyll?
the green pigment largely responsible for trapping light energy, making it available for the plant to use in photosynthesis
What are amlyoplasts?
plant organelles that store starch
