module 2 - foundations in biology

Question 1

what are the 3 types of potencies for stem cells

Answer 1

totipotent
pluripotent
multipotent

Question 2

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

Answer 2

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

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

what are the two things stem cells can do

Answer 5

self renewal, where identical stem cells are made

differentiation, the making a specialised cell from a stem cell

Question 6

what are the levels of organisation within an organism

Answer 6

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

Question 7

why are erythrocytes made in the bone marrow, and how

Answer 7

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

made via erythropoiesis (subform of haemopoiesis)

Question 8

how does erythropoiesis work

Answer 8

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

Question 9

what adaptations do erythrocytes have and why

Answer 9

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

Question 10

what main changes occur when stem cells differentiate into neutrophils

Answer 10

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)

Question 11

where does mitosis occur most in plants

Answer 11

meristematic tissue (roots and shoots) for growth

Question 12

what are the xylem and phloem formed from

Answer 12

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

Question 13

what stimulates cell differentiation

Answer 13

hormones/balance of different hormones

Question 14

name all stem cell sources

Answer 14

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

Question 15

define a stem cell

Answer 15

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

Question 16

what can stem cells be used for

Answer 16

repair of damaged tissues,

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

Question 17

what are the controversies surrounding embryonic stem cells

Answer 17

could’ve potentially been a living person

usually wasted from ivf

Question 18

what can be dangerous about tissue transplants

Answer 18

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

Question 19

how many types of microscopes are there?

Answer 19

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

Question 20

what two key features of microscopes are needed for microscopy

Answer 20

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)

Question 21

describe the features of an optical/light microscope

Answer 21

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

Question 22

what is the advantages and disadvantages of electron vs photon microscopes

Answer 22

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

Question 23

what can be seen with electron microscopes

Answer 23

ribosomes, lysosomes, endoplasmic reticulum, viruses

Question 24

what two types of electron microscopes are there

Answer 24

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

Question 25

pros and cons of scanning/transmission

Answer 25

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

Question 26

explain laser scanning confocal microscopes

Answer 26

``` 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 ```

Question 27

how to prepare specimens for light microscopy

Answer 27

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

Question 28

what is each light microscope preparation techniques used for

Answer 28

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

Question 29

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

Answer 29

gram stain and acid fast technique | dangerous because many stains are toxic or irritants

Question 30

name some common dyes

Answer 30

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)

Question 31

outline the method of the gram stain technique

Answer 31

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

Question 32

what is the importance of gram staining

Answer 32

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

Question 33

outline the technique for acid fast

Answer 33

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

Question 34

what are the key features of eukaryotic cells

Answer 34

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

Question 35

what cell features are present in plant but not animal cells

Answer 35

cellulose cell wall, chloroplasts, permanent vacuoles

Question 36

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

Answer 36

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

Question 37

describe structure of nucleus and surrounding regions

Answer 37

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

Question 38

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

Answer 38

inner and outer membrane | inner membrane folding called cristae

Question 39

why are some organelles membrane bound and where are they found

Answer 39

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

Question 40

discuss the organelles involved in protein synthesis and secretion

Answer 40

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

Question 41

what is the function of the cytoskeleton

Answer 41

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

Question 42

function of S.E.R.

Answer 42

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

Question 43

how big are each sizes are ribosomes

Answer 43

prokaryote - small, 70s | eukaryote - big, 80s

Question 44

what do you use to calibrate the eyepiece graticule

Answer 44

the stage micrometer

Question 45

what does dna associate with to form chromatin

Answer 45

histones

Question 46

what are the layers in a section of a stem

Answer 46

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

Question 47

name of all sugar types

Answer 47

monosaccharide - glucose, fructose, galactose disaccharide - maltose, sucrose, lactose polysaccharide - amylose, amylopectin, glycogen, cellulose

Question 48

what are the building blocks of each type of biological molecules

Answer 48

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

Question 49

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

Answer 49

``` 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 ```

Question 50

what is the name of the bonds between monosaccharide molecules

Answer 50

glycosidic, formed by condensation reaction

Question 51

when are 1-6 glycosidic bonds present

Answer 51

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

Question 52

beta glucose is present in which molecule

Answer 52

cellulose