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biology a level ocr > module 2 - foundations in biology > Flashcards

module 2 - foundations in biology Flashcards

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1
Q

what are the 3 types of potencies for stem cells

A

totipotent
pluripotent
multipotent

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2
Q

what cells can totipotent stem cells differentiate into, and where are they from

A

can become any type of cell, and are from zygotes (first 8-16 divisions)

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3
Q

what can pluripotent stem cells differentiate into, and where are they from

A

can become any tissue type, but not a whole organism, and are from inside layer of blastocyst cells

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4
Q

what can multipotent stem cells differentiate into, and where are they from

A

can become any cell type within a tissue, and can be harvested from the adult body (bone marrow, skin, testes, intestine, cardiac cells, brain)

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5
Q

what are the two things stem cells can do

A

self renewal, where identical stem cells are made

differentiation, the making a specialised cell from a stem cell

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6
Q

what are the levels of organisation within an organism

A

cells are organised into tissues, then organs, then organ systems, then organism
e.g. neurons, nervous tissue, brain, CNS, badger

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7
Q

why are erythrocytes made in the bone marrow, and how

A

need to be made because they have no nucleus, so no mitosis

made via erythropoiesis (subform of haemopoiesis)

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8
Q

how does erythropoiesis work

A

multipotent cell form proerythrocytes
haemoglobin builds up in cytoplasm
nucleus is ejected
further changes make the cell a mature erythrocyte (biconcave shape etc)

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9
Q

what adaptations do erythrocytes have and why

A

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

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10
Q

what main changes occur when stem cells differentiate into neutrophils

A 
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)
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11
Q

where does mitosis occur most in plants

A

meristematic tissue (roots and shoots) for growth

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12
Q

what are the xylem and phloem formed from

A

the cambium - meristematic tissue between the phloem and xylem in stems and roots

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13
Q

what stimulates cell differentiation

A

hormones/balance of different hormones

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14
Q

name all stem cell sources

A

inside layer of embryos, bone marrow, skin, liver, brain, intestines, umbilical cord blood, tips of roots and shoots

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15
Q

define a stem cell

A

a cell that can divide an unlimited number of times via mitosis, and can differentiate into other cells

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16
Q

what can stem cells be used for

A

repair of damaged tissues,

treatment for alzheimer’s, parkinson’s, type 1 diabetes, blood diseases and research into developmental biology

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17
Q

what are the controversies surrounding embryonic stem cells

A

could’ve potentially been a living person

usually wasted from ivf

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18
Q

what can be dangerous about tissue transplants

A

the immune system may consider it antigenic and attack it (esp blood type)

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19
Q

how many types of microscopes are there?

A

light (also called optical)
laser scanning confocal
scanning electron
transmission electron

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20
Q

what two key features of microscopes are needed for microscopy

A 
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)
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21
Q

describe the features of an optical/light microscope

A

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

22
Q

what is the advantages and disadvantages of electron vs photon microscopes

A 
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
23
Q

what can be seen with electron microscopes

A

ribosomes, lysosomes, endoplasmic reticulum, viruses

24
Q

what two types of electron microscopes are there

A

transmission (needs thin specimen) - show high resolution with internals
scanning (use thick/3D) - show 3D structure and external of specimen

25
Q

pros and cons of scanning/transmission

A

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

26
Q

explain laser scanning confocal microscopes

A 
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
27
Q

how to prepare specimens for light microscopy

A

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

28
Q

what is each light microscope preparation techniques used for

A

hair, pollen, muscle tissue, plants - dry mount
aquatic samples that live in the water - wet mount
root tips - squash slides
blood - smear slides

29
Q

what are the two main differential staining techniques, and what dangers are associated

A

gram stain and acid fast technique

dangerous because many stains are toxic or irritants

30
Q

name some common dyes

A

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)

31
Q

outline the method of the gram stain technique

A

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

32
Q

what is the importance of gram staining

A

gram negative have thin cell walls, so are not susceptible to penicillin

33
Q

outline the technique for acid fast

A

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

34
Q

what are the key features of eukaryotic cells

A

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

35
Q

what cell features are present in plant but not animal cells

A

cellulose cell wall, chloroplasts, permanent vacuoles

36
Q

what is the function of the cell surface membrane + its structure

A

to control the exchange of membranes and maintain concentration gradients
phospholipid bilayer - 10nm

37
Q

describe structure of nucleus and surrounding regions

A

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

38
Q

how many membranes do mitochondria have, and what are the foldings of their membrane called

A

inner and outer membrane

inner membrane folding called cristae

39
Q

why are some organelles membrane bound and where are they found

A

eukaryotic cells, maintain concentration gradients, compartmentalisation, provide a site for reactions

40
Q

discuss the organelles involved in protein synthesis and secretion

A

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

41
Q

what is the function of the cytoskeleton

A

movement, mitosis (mitotic spindles, cytokinesis), formation of pseudopodia, movement (cilia, flagella), cellular support

42
Q

function of S.E.R.

A

production and storage of lipids like phospholipids and cholesterols for creation/maintenance of bilayer

43
Q

how big are each sizes are ribosomes

A

prokaryote - small, 70s

eukaryote - big, 80s

44
Q

what do you use to calibrate the eyepiece graticule

A

the stage micrometer

45
Q

what does dna associate with to form chromatin

A

histones

46
Q

what are the layers in a section of a stem

A

outer - phloem, middle cambium, outer xylem (big holes)

47
Q

name of all sugar types

A

monosaccharide -
glucose, fructose, galactose

disaccharide -
maltose, sucrose, lactose

polysaccharide -
amylose, amylopectin, glycogen, cellulose

48
Q

what are the building blocks of each type of biological molecules

A

C H O for carbohydrates and lipids
C H O N S for proteins
C H O N P for nucleic acids

49
Q

what properties does water have that makes it suitable to sustain life

A 
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
50
Q

what is the name of the bonds between monosaccharide molecules

A

glycosidic, formed by condensation reaction

51
Q

when are 1-6 glycosidic bonds present

A

whenever a molecule is branched i.e. glycogen and amylopectin

52
Q

beta glucose is present in which molecule

A

cellulose

biology a level ocr (2 decks)

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