Chapter 2 - basic components of living systems Flashcards
what is magnification?
how many times larger the image is than the actual size of the object being viewed
what is resolution?
the ability to see individual objects as separate entities
transmission electron microscope (TEM)
- a beam of electrons is transmitted through a specimen and focused to produce an image
- resolution power 0.5nm
scanning electron microscope (SEM)
- a beam of electrons sent across the surface of a specimen and the reflected electrons are collected
- resolution power 3-10nm
- produce 3D images of surface
laser scanning confocal microscope
- moves a single spot of focused light across a specimen
- very thin sections of specimen examined
- light from elsewhere removed
- produce very high resolution images
- non invasive
what is the nucleus?
- contains coded genetic info in form of DNA
- has a nuclear envelope (double membrane) that contains nuclear pores allowing molecules to move in and out of nucleus
what is DNA?
- directs the synthesis of proteins
- controls metabolic activity of the cell
- associates with proteins called histones to form chromatin (forms chromosomes)
what is the nucleolus?
- an area within the nucleus responsible for producing ribosomes
- composed of proteins and RNA (RNA used to produce rRNA)
what is the structure mitochondria?
- double membrane
- inner membrane folded to form cristae
- fluid interior called matrix
what is the function of the mitochondria?
- site of the final stages of cellular respiration
- produces ATP
what are vesicles?
- membranous sacs
- have storage and transport roles
- used to transport materials inside the cell
what are lysosomes?
- specialised forms of vesicles
- contain hydrolytic enzymes
- break down waste material in cells
- responsible for breaking down pathogens ingested by phagocytic cells
what is the cytoskeleton?
- a network of fibres necessary for the shape and stability of a cell
- holds organelles in place and controls movement of the cell and organelles
what are the three components of the cytoskeleton?
- microfilaments: contractile fibres formed from protein actin, responsible for cell movements and contraction during cytokinesis
- microtubules: globular tubulin proteins polymerised to form tubes, determine the shape of the cell, e.g. spindle fibres
-intermediate fibres: give mechanical strength to cells, help maintain integrity
what are centrioles?
- composed of microtubules
- involved in the assembly and organisation of spindle fibres during cell division
what is the smooth endoplasmic reticulum (SER)?
- responsible for lipid and carbohydrate synthesis and storage
what is the rough endoplasmic reticulum (RER)?
- has ribosomes bound to surface
- responsible for the synthesis and transport of proteins
what are ribosomes?
- constructed of RNA molecules
- the site of protein synthesis
what is the golgi apparatus?
- has a role in modifying and packaging proteins into vesicles
what are the stages of protein production?
1) proteins synthesised on the ribosomes bound to endoplasmic reticulum
2) proteins pass into cisternae and packaged into transport vesicles
3) vesicles move towards golgi apparatus via cytoskeleton
4) vesicles fuse with cis face of golgi apparatus and proteins enter. the proteins are modified and leave into vesicles via trans vis
5) secretory vesicles carry proteins towards and fuse with cell surface membrane releasing contents
what is the structure and function of cellulose cell wall?
- made of cellulose (a carbohydrate)
- freely permeable
- give the plant shape (contents of cell press up against cell wall to make it rigid)
- acts as a defence mechanism
what are vacuoles?
- membrane lined sacs in the cytoplasm containing cell sap
- important in maintaining turgor so that cell contents push up against cell wall
- has a membrane called tonoplast
-selectively permeable
what are chloroplast?
- organelles responsible for photosynthesis
- found in green parts of plant (leaves and stems)
- have a double membrane structure
- fluid enclosed called stroma
- contain thylakoids that stack to from grana
-grana joined by lamellae
-starch grain (starch produced by photosynthesis)
-contain DNA and ribosomes
