Chapter 3 - Cell Structure Flashcards
What is the formulae for magnification?
“I AM” , Image over actual size times magnification
What must be done to a sample before cell fractionation? 3
cold - slow enzymes involved in autolysis
isotonic - stop shrinking/bursting (of organelles)
buffered - stop fluctuation in pH, no denatured proteins
What is homogenation?
blender, break down of cells
what is the resultant fluid of homogenation known as?
homogenate
outline the steps of ultracentrifugation (3)
- homogenate spun at low speed
- nuclei forced to bottom forming a pellet
- supernantent removed and spun again at higher speed
what must happen to the homogenate before ultracentrifugation?
filtered, removes cell walls/membranes
what is resolution?
the minimum distance apart that two objects can be in order for them to appear as separate items
what is the resolving power of TEM
0.1nm
what is the resolving power of SEM
20nm
what is the resolving power of a light microscope
0.2 micrometers
why can the highest resolving power of TEM not always be achieved? (2)
- artefacts from prep
- higher energy electron beam needed which may destroy the specimen
what are the limitations of TEM? (4)
- vacuum (organisms must be dead)
- complex staining process
- extremely thin specimen
- artefacts from extensive prep process and many chemicals
What is the name of the image the TEM produces?
photomicrograph
what is an eyepiece graticule?
glass disc placed in eyepiece with scale etched on
how would you calibrate the eyepiece graticule? (3)
- use stage micrometer with scale
- find where both scales line up
- known value of micrometer allows calculation of graticule units and magnification
state the features of the nucleus (5)
- nuclear envelope (double membrane)
- nuclear pores (for mRNA)
- jelly like nucleoplasm
- chromosomes
- nucleolus (manufactures ribosomal RNA and ribosomes)
what are the functions of the nucleus? (3)
- control centre of cell, protein synthesis
- retain chromosomes
- manufacture ribosomal RNA and ribosomes
what are the structures of the mitochondria? (3)
- double membrane
- cristae, Large SA for ETC
- matrix
function of mitochondria? (2)
- site of aerobic respiration
- ATP from glucose
features of a chloroplasts? (3)
- chloroplast envelope , double
- grana (stacks of thylakoids) which contain chlorophyll
- stroma, LI
functions of a chloroplast? (3)
- granal membranes = large SA for LD
- stroma contains all enzymes for LI
- contain DNA + ribosomes for protein synthesis
what is the ER? (2)
- 3D system of sheet-like membranes, continuous with outer membranes of nuclear membrane
- membrane encloses sacs called cisternae
functions of SER?
synthesize, store and transport lipids and carbohydrates
functions of RER? (2)
- large SA for synthesis of proteins/ glycoproteins
- transport of proteins in cell
what are golgi apparatus? (2)
- flattened sacs (cisternae) with vesicles
- adds non protein components and modifies proteins from ER
functions of golgi? (4)
- add carbs to form glycoproteins
- produce secretory enzymes
- secrete carbohydrates
- transport, modify, store lipids from lysosomes
what are lysosomes?
vesicles containing hydrolytic enzymes
function of lysosomes? (4)
- hydrolyse material ingested by phagocytic cells
- excocytosis for humoural breakdown
- digest worn out organelles
- autolysis
Types of ribosomes? (2)
80s - eukaryotic cells
70s - prokaryotic cells
what are ribosomes made up of? (2)
2 sub units
- 1 large sub unit
- 1 small sub unit
features of a cell wall? (2)
- polysaccharides e.g. cellulose/chitin
- thin layer called middle lamella marks boundary between cells and cements them together
functions of cellulose cell wall? (3)
- mechanical strength - stop bursting
- mechanical strength to whole plant
- allow water to pass along it through middle lamella
what are vacuoles?
fluid filled sac - single membrane
functions of vacuoles? (3)
- support herbacious plants by making cells turgid
- sugars and amino acids act as temporary food store
- pigments colour to attract insects for pollination
what is the cell ultrastructure?
the specific internal structure adapted for the cells task
how do cells become specialised? (2)
- all contain the same genes
- only certain genes expressed in one cell
what is a tissue?
collection of similar cells e.g. epethelial cells
what is an organ?
a combination of tissues coordinated to perform a variety of functions usually one major function
give 3 examples of organ systems
- digestive
- respiratory
- circulatory
what are eukaryotes?
larger - with a nucleus
what are prokaryotes?
smaller - no nucleus or nuclear envelope + plasmids
compare the structures of eukaryotes/prokaryotes from the perspective of prokaryotes (9)
- no nuleus
- no nuclear envelope
- DNA not associated with proteins
- plasmids
- no membrane-bound organelles
- no chloroplasts
- smaller ribosomes
- cell wall made of murien
- slime capsule
what are viruses?
acellular, non living particles
what is the order of mitosis? (6)
I P M A T C
what happens in the cell during interphase? (2)
- DNA replication, chromosomes remain joined at centromere
- replication of organelles
what happens during prophase? (2)
- chromosomes become visible, shorten/thicken
- spindle fibres develop
what happens during metaphase?
chromosomes line up at equator
what happens during anaphase? (3)
- centromeres divide into 2
- pulling apart chromatids
- energy for spindle fibres by mitchondria
what happens during telophase/cytokinesis? (4)
- chromosomes reach poles - dissapear
- spindle fibres disintegrate
- nuclear envelope reforms
- cytoplasm divides
outline the cell division in prokaryotes (6)
- circular DNA replicate
- both attach to membrane
- plasmids also replicate
- cell membrane grows between DNA molecules - pinch inwards
- cell wall forms between DNA forming identical daughter cells
- variable no. plasmids
3 stages of the cell cycle?
- interphase
- nuclear division
- division
how do chemotherapy drugs prevent cells replicating? (2)
- prevent DNA replication
- interfering with spindle fibre formation
