module 2 - foundations in biology Flashcards
what are the 3 types of potencies for stem cells
totipotent
pluripotent
multipotent
what cells can totipotent stem cells differentiate into, and where are they from
can become any type of cell, and are from zygotes (first 8-16 divisions)
what can pluripotent stem cells differentiate into, and where are they from
can become any tissue type, but not a whole organism, and are from inside layer of blastocyst cells
what can multipotent stem cells differentiate into, and where are they from
can become any cell type within a tissue, and can be harvested from the adult body (bone marrow, skin, testes, intestine, cardiac cells, brain)
what are the two things stem cells can do
self renewal, where identical stem cells are made
differentiation, the making a specialised cell from a stem cell
what are the levels of organisation within an organism
cells are organised into tissues, then organs, then organ systems, then organism
e.g. neurons, nervous tissue, brain, CNS, badger
why are erythrocytes made in the bone marrow, and how
need to be made because they have no nucleus, so no mitosis
made via erythropoiesis (subform of haemopoiesis)
how does erythropoiesis work
multipotent cell form proerythrocytes
haemoglobin builds up in cytoplasm
nucleus is ejected
further changes make the cell a mature erythrocyte (biconcave shape etc)
what adaptations do erythrocytes have and why
biconcave shape - increase surface area
haemoglobin builds up - haemoglobin binds to oxygen
ejection of organelles - more room for haemoglobin
elastic membrane - allow cell to fit in capillaries
what main changes occur when stem cells differentiate into neutrophils
indentations in nucleus give it a lobed structure (squeeze in capillaries) granules accumulate (lysosomes that contain hydrolytic enzymes) flexible shape (allow it to phagocytose pathogens)
where does mitosis occur most in plants
meristematic tissue (roots and shoots) for growth
what are the xylem and phloem formed from
the cambium - meristematic tissue between the phloem and xylem in stems and roots
what stimulates cell differentiation
hormones/balance of different hormones
name all stem cell sources
inside layer of embryos, bone marrow, skin, liver, brain, intestines, umbilical cord blood, tips of roots and shoots
define a stem cell
a cell that can divide an unlimited number of times via mitosis, and can differentiate into other cells
what can stem cells be used for
repair of damaged tissues,
treatment for alzheimer’s, parkinson’s, type 1 diabetes, blood diseases and research into developmental biology
what are the controversies surrounding embryonic stem cells
could’ve potentially been a living person
usually wasted from ivf
what can be dangerous about tissue transplants
the immune system may consider it antigenic and attack it (esp blood type)
how many types of microscopes are there?
light (also called optical)
laser scanning confocal
scanning electron
transmission electron
what two key features of microscopes are needed for microscopy
high magnification (how many times bigger things can look than they are) high resolution (how close two things can be together while remaining visually distinct)
describe the features of an optical/light microscope
resolution of 0.2 micrometres/200 nanometres
max magnification is around 1500x (but usually 400x)
can see cells, nuclei, mitochondria and chloroplasts, but not smaller
what is the advantages and disadvantages of electron vs photon microscopes
electron microscopes are higher resolution as electrons are smaller much more expensive specimen must be dead no colour (no light) 500,000x magnification for electron
what can be seen with electron microscopes
ribosomes, lysosomes, endoplasmic reticulum, viruses
what two types of electron microscopes are there
transmission (needs thin specimen) - show high resolution with internals
scanning (use thick/3D) - show 3D structure and external of specimen
pros and cons of scanning/transmission
scanning lower resolution
transmission can have artefacts due to staining/preserving
can show either 3D structure or internal structure of specimen
TEM 0.5nm, SEM 3-10nm
explain laser scanning confocal microscopes
cells viewed using fluorescent dyes thick section is used laser reflected by dyes like a cat scan, builds 3D through layers of 2D scans slow, can cause photodamage
how to prepare specimens for light microscopy
section into thin slices - dry mount
place cover slip on at angle - wet mount
lightly squash slide prepared like wet mount - squash slides
slide edge used to smear sample, then wet mount - smear slides
what is each light microscope preparation techniques used for
hair, pollen, muscle tissue, plants - dry mount
aquatic samples that live in the water - wet mount
root tips - squash slides
blood - smear slides
what are the two main differential staining techniques, and what dangers are associated
gram stain and acid fast technique
dangerous because many stains are toxic or irritants
name some common dyes
crystal violet + methylene blue are positive, attracted to negatively charged materials in cytoplasm
nigrosin + congo red are negative, so repelled by negative cytoplasm (stain the background)
outline the method of the gram stain technique
separates bacteria into two groups - positive and negative
crystal violet is applied
iodine then added (fixes the dye)
washed with alcohol, thin cell walls lose the stain (gram negative bacteria)
then stained with safranin as a counterstain
this makes the gram negative appear red, and the gram positive look blue from the crystal violet
what is the importance of gram staining
gram negative have thin cell walls, so are not susceptible to penicillin
outline the technique for acid fast
used to separate mycobacterium from other bacteria
lipid solvent with carbolfuchsin dye added
then washed with acid-alcohol solution
mycobacterium keep carbolfuchsin (red)
those that lose stain are counterstained with methylene blue
what are the key features of eukaryotic cells
cell wall, cell surface membrane, nucleus, mitochondria, chloroplasts, ribosomes, smolth and rough endoplasmic reticulum, golgi apparatus, permanent vacuoles, vesicles, lysosomes, centrioles, microtubules, microvilli, cillia, flagella
what cell features are present in plant but not animal cells
cellulose cell wall, chloroplasts, permanent vacuoles
what is the function of the cell surface membrane + its structure
to control the exchange of membranes and maintain concentration gradients
phospholipid bilayer - 10nm
describe structure of nucleus and surrounding regions
nucleolus in centre - makes ribosomes
chromatin surrounding it - made of dna
nuclear envelope surrounding it - keep it contained
nuclear pores allow mrna and ribosomes to be transported
rough and then smooth endoplasmic reticulum
how many membranes do mitochondria have, and what are the foldings of their membrane called
inner and outer membrane
inner membrane folding called cristae
why are some organelles membrane bound and where are they found
eukaryotic cells, maintain concentration gradients, compartmentalisation, provide a site for reactions
discuss the organelles involved in protein synthesis and secretion
mRNA moves from nucleus through nuclear pores after transcription
arrives at ribosomes for translation
amino acids form polypeptide, fold into quaternary structure
packaged into vesicles, moves via cytoskeleton and transport proteins into golgi apparatus
packaged and processed at golgi, then membranes pinches into vesicle and is transported for exocytosis
what is the function of the cytoskeleton
movement, mitosis (mitotic spindles, cytokinesis), formation of pseudopodia, movement (cilia, flagella), cellular support
function of S.E.R.
production and storage of lipids like phospholipids and cholesterols for creation/maintenance of bilayer
how big are each sizes are ribosomes
prokaryote - small, 70s
eukaryote - big, 80s
what do you use to calibrate the eyepiece graticule
the stage micrometer
what does dna associate with to form chromatin
histones
what are the layers in a section of a stem
outer - phloem, middle cambium, outer xylem (big holes)
name of all sugar types
monosaccharide -
glucose, fructose, galactose
disaccharide -
maltose, sucrose, lactose
polysaccharide -
amylose, amylopectin, glycogen, cellulose
what are the building blocks of each type of biological molecules
C H O for carbohydrates and lipids
C H O N S for proteins
C H O N P for nucleic acids
what properties does water have that makes it suitable to sustain life
high latent heat of vaporisation high specific heat capacity high cohesion and adhesion common on earth's surface mostly liquid on the planet surface solid is less dense than liquid on acc of hydrogen bonding
what is the name of the bonds between monosaccharide molecules
glycosidic, formed by condensation reaction
when are 1-6 glycosidic bonds present
whenever a molecule is branched i.e. glycogen and amylopectin
beta glucose is present in which molecule
cellulose
