About our Book
Hi everyone! Hannah here. As college students, my friend Emily and I are studying from home. We realized you probably are working from home too, and might not quite know why. So we put together this book to try and explain viruses- the annoying buggers behind the coronavirus and even the common cold. We hope you enjoy it and learn some new things about science too!
Copyright © 2020 Hannah Margolis
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Permission is granted to distribute this publication in its entirety, without change and without charge.Otherwise, however, all rights reserved and no part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law.ISBN: 978-1-7923-4213-

Margolis, Hannah K

Morin, Emily J

English

Dartmouth Digital Commons (Dartmouth College)

Dartmouth College Dartmouth Digital Commons Independent Student Projects Other Student Work 2020 What is a Virus? Hannah K. Margolis Dartmouth College, Hannah.K.Margolis.20@dartmouth.edu Emily J. Morin Dartmouth College Follow this and additional works at: https://digitalcommons.dartmouth.edu/student_projects Dartmouth Digital Commons Citation Margolis, Hannah K. and Morin, Emily J., "What is a Virus?" (2020). Independent Student Projects. 1. https://digitalcommons.dartmouth.edu/student_projects/1 This Book is brought to you for free and open access by the Other Student Work at Dartmouth Digital Commons. It has been accepted for inclusion in Independent Student Projects by an authorized administrator of Dartmouth Digital Commons. For more information, please contact dartmouthdigitalcommons@groups.dartmouth.edu. What	is	avirus?Written	by	Hannah	K.	MargolisIllustrated	by	Emily	J.	Morin	1	Copyright	©		2020	Hannah	Margolis	Permission	is	granted	to	distribute	this	publication	in	its	entirety,	without	change	and	without	charge.Otherwise,	however,	all	rights	reserved	and	no	part	of	this	publication	may	be	reproduced,	distributed,	or	transmitted	in	anyform	or	by	any	means,	including	photocopying,	recording,	or	other	electronic	or	mechanical	methods,	without	the	prior	writtenpermission	of	the	author,	except	in	the	case	of	brief	quotations	embodied	in	critical	reviews	and	certain	other	noncommercialuses	permitted	by	copyright	law.ISBN:	978-1-7923-4213-4Protected	by	Creative	Commons.	Attribution-NonCommercial	4.0	International	(CC	BY-NC	4.0).	You	may	reproduce	thiswork	for	noncommercial	purposes	with	appropriate	credit.Image	References	Hooke's	microscope:	Robert	Hooke(Life	time:	March	3rd,	1703)	/	Public	domain	available	at	https://commons.wikimedia.org/wiki/File:Robert_Hooke%27s_microscope.png	Hooke's	cork	cell	image:	"cells	in	cork	oak	from	Robert	Hooke"	by	Martin	LaBar	is	licensed	under	CC	BY-NC	2.0	Availableat	https://search.creativecommons.org/photos/12979c22-5684-43df-93bb-71f2e06fe18d			Van	Leeuwenhock	portrait:	"File:Portrait	of	A.	van	Leeuwenhoek,	1686	Wellcome	M0004947.jpg"	is	licensed	under	CC	BY4.0	Available	at	https://search.creativecommons.org/photos/be26ecba-96a6-4c95-be81-a036e329e309			Rosalind	Franklin:	"File:Rosalind	Franklin	(retouched).jpg"	by	MRC	Laboratory	of	Molecular	Biology	is	licensed	under	CCBY-SA	4.0	Available	at	https://search.creativecommons.org/photos/c775ae4b-648c-4b46-bfe2-6dfc1b3c790b	X-ray	diffraction	and	TMV	sketch:	Reprinted	by	permission	from	Springer	Nature	Customer	Service	Centre	GmbH:Springer	Nature	NATURE.	Structure	of	Tobacco	Mosaic	Virus,	Rosalind	Franklin,	1955.			TMV	Structure:	"File:TMV	structure	full.png"	by	Thomas	Splettstoesser	(www.scistyle.com)	is	licensed	under	CC	BY-SA	3.0Available	at	https://search.creativecommons.org/photos/039626ec-de9a-478e-a00e-9d8a10d4f187	Author	and	Illustrator	can	be	reached	at	whatisavirusbook@gmail.com	2	If	you	normally	go	to	school	during	the	day,	you've	probablynoticed	things	have	changed.	Kids	aren't	going	to	school	People	aren't	hangingout	in	groups.	3	You	might	wonder	why.	Your	parents	might	be	working	from	home.	You're	probably	trying	to	stay	busy	at	home	too!Check	out	the	chemistryset	my	stepdad	got	me	tokeep	busy!Will	you	bedone	soon?Let's	gooutside!Ssh!	Mom	is	working!	4	It's	just	too	small	to	see	with	your	eyes.	The	reason	is	that	there	is	something	new	movingaround...	5	The	new	thing	is	called	a	virus.		6	...just	too	small	to	see.Just	how	small	is	a	virus?	A	Question	of	Scale	When	we	say	a	virus	is	small,	how	small	are	we	talking?	You’re	probably	used	to	comparing	the	sizes	of	objects	like	a	walnut	to	a	watermelon.	But	what	if	we	want	to	compare	the	sizes	of	two	very	different	things,	like	the	size	ofthe	moon	to	the	size	of	that	walnut?	That’s	a	pretty	big	difference!Scientists	explain	these	differences	in	powers	of	ten.	For	instance,	a	watermelon	(around	40	cm	long)	is	about	10	timeslarger	than	a	walnut	(4.5	cm	long)	and	the	moon	(3474	km	in	diameter)	is	10	million	times	larger	than	that	walnut	(that’s1	with	seven	zeroes:	10,000,000!)	This	is	the	level	of	scale	we	need	to	describe	viruses.	On	average,	a	virus	(100	nm)	is	1	million	(1,000,000)	timessmaller	than	the	watermelon.	In	other	words,	a	virus	is	so	small	compared	to	a	watermelon,	it	is	similar	to	comparing	awatermelon	to	the	moon!	Viruses	are	all	around	us...(We'd	have	to	zoom	inREALLY	far	to	see	theviruses!)	7	In	fact,	you've	probably	been	in	contact	with	a	virus	before.	But	what	are	viruses,	and	how	do	they	make	us	sick?	I	had	the	flu	a	fewmonths	ago	and	hadto	stay	home	fromschool!My	little	brother	just	got	over	acold.	Both	the	cold	and	flu	arecaused	by	viruses!	8	This	might	sound	weird,	but	mostscientists	believe	viruses	aren't	aliveWhat	makes	something	alive?			This	might	seem	like	a	silly	question.	Butbelieve	it	or	not,	many	scientists	disagree	onwhat	exactly	makes	something	alive!While	some	things,	like	a	fish	or	flower,	aredefinitely	alive,	what	about	parts	of	livingthings?	Is	your	foot	alive?	A	bone	from	dinner?In	general,	scientists	do	agree	that	to	be	alive,something	must:	•Be	able	to	move	•Take	in	energy	from	food	•Notice	and	respond	when	something	aroundyou	changes	•Grow	•Reproduce	•Maintain	homeostasis-	a	fancy	term	meaningyou	can	keep	things	in	your	body	constant,	likeyour	body	temperature	even	if	it's	cold	outside.Think	about	something	living-	like	a	tree,	adog,	or	yourself.	Do	you	meet	all	of	thesecategories?	What	about	something	like	fire?	(This	one	is	tricky!	Hint:	can	fires	maintainhomeostasis?)	Although	some	scientists	debate	it,	viruses	arenormally	not	considered	alive	because	theycannot	reproduce	on	their	own	and	do	not	takein	energy	from	food.	Things	like	plants	andanimals	are	alive-	butviruses	aren't!	9	The	outside	is	made	of	twomaterials	called	protein	andlipids.	The	inside	holds	geneticmaterial:	either	DNA	or	RNA.	Viruses	are	just	containersCurrent	TMV	StructureFranklin's	sketchWith	these	images,	she	figured	out	that	thevirus	had	protein	on	the	outside	and	DNA	onthe	inside.	She	even	made	sketches	of	thestructure	that	are	very	close	to	the	structure	ofthe	virus	we	have	today!In	the	1950s,	a	chemistnamed	RosalindFranklin	collected	someof	the	first	data	on	thestructure	of	viruses.	Shestudied	TMV,	a	virusthat	infects	plants.	We	said	earlier	that	viruses	are	really	small–	thousands	of	times	smaller	than	a	pin.	Sohow	do	we	know	what	they	look	like?	How	do	we	know	what	viruseslook	like?	Rosalind	Franklin	andTobacco	Mosaic	VirusFranklin	used	a	complexmethod	called	x-raycrystallography	to	getdiffraction	images	likethis	one.	Dr.	Franklin	at	work	10	Viruses	come	in	many	varieties	withAlphainfluenzavirus	Common	Flu	80-120	nanometers	(nm)Rhinovirus	Common	Cold	30	nm	Myoviridae	Bacteriaphage	Infect	bacteria!		Approx	200	nm	Lentivirus	HIV/AIDS	120	nm	Variola	major	and	minor	Small	pox	(eradicated)	250	x	300	nm	Zaire	ebolavirus	Ebola	800-1000	nm	long!	(Eradicated	meansthe	virus	is	nowgone	thanks	tomedical	efforts.)	11	Rabies	lyssavirus	Rabies	180	nm	long	Human	alphaherpesvirus	3	Chickenpox	200	nm	different	protein	coats.These	different	protein	coats	allowviruses	to	make	us	sick.	How?Scientists	are	working	hard	to	find	ways	to	treatand	prevent	Coronavirus,	but	everyone	must	helpprevent	the	spread	of	the	virus	so	life	can	return	tonormal.		You	might	have	heard	about	 something	called	 theCoronavirus	recently.	The	Coronavirus	is	a	sickness,	like	a	flu	or	the	cold.But	 unlike	 the	 flu	 or	 the	 cold,	 coronavirus	 is	 arespiratory	illness.	This	means	it	affects	how	wellyour	lungs	can	help	you	breathe.	Signs	that	you’re	sick	(called	symptoms)	includeshortness	of	breath,	a	dry	cough,	fever,	and	chills.	Coronavirus	is	caused	by	a	virus	that	didn’t	existbefore,	called	SARS-CoV-2.	It	is	related	to	otherviruses	that	also	cause	respiratory	illness.	The	virus	can	be	spread	whensomeone	who	is	sick	coughs	ortouches	their	mouth	or	nose.	SARS-CoV-2	has	caused	apandemic,	meaning	it	hasinfected	many	people	allaround	the	world.	Part	of	the	reason	it	is	sosuccessful	is	that	manypeople	who	get	coronavirusdon’t	feel	that	sick	andSARS-CoV-2	The	2020	Coronavirus	outbreak	SARS-CoV-2	Coronavirus	120	nm	spread	it	when	they	go	about	their	daily	plans.	12	To	answer	that,	we	need	to	imagine	being	on	the	scaleof	a	virus,	because	viruses	are	very,	very,	very,	very	tinyTake	a	closeup	look	at	your	hands-	what	do	you	see?	But	what	if	we	zoomed	in	to	a	higher	resolution	than	your	eyes	can	see?'Resolution'	is	a	fancy	word	for	thesmallest	thing	something	can	see.	Our	eyeshave	a	resolution	of	about	0.1	mm.	That'sa	bit	smaller	than	the	width	of	yourfingernail. Even	with	a	magnifying	glassI	can't	see	the	cells	thatmake	up	my	hand.	Take	a	look	at	your	hand	in	amagnifying	glass-	you	can	see	morethan	with	your	eyes	alone!	13	We	can	do	this	with	a	verypowerful	microscopeNow	you	can	see	that	your	hand	ismade	up	of	many	smaller	parts,	calledcellsDid	you	know	your	body	is	madeup	of	over	30	trillion	cells?That's	more	than	8000	timesthe	number	of	stars	in	ourgalaxy!		A	view	of	cells	in	the	microscopeSeeing	Cells-the	pioneers	ofmicroscopes	In	1665,	Robert	Hooke	was	the	first	person	touse	the	term	”cells”	to	describe	the	tinycomponents	of	a	plant	under	the	microscope.He	compared	them	to	arranged	pieces	of	ahoneycomb	from	a	bee	hive	in	his	famous	bookMicrographia.	Hooke	was	a	naturalist	from	England	withinterests	ranging	from	map	making	to	theplanets,	fossils,	and	living	things.	Later	in	life,Hooke	worried	other	scientists	would	take	hisideas,	and	started	recording	his	work	in	code.	Antony	Van	Leeuwenhoek	iscalled	the	“Father	ofMicrobiology”.	In	the	1670s,he	made	new	microscopelenses	that	could	magnifymuch	better.	He	discoveredsingle	celled	organismsincluding	bacteria	andprotists	(which	he	called“wee	beasties”)	by	examining	things	such	asthe	plaque	he	scraped	off	of	his	teeth.Hooke's	microscope A	sketch	of	plantcells	Hooke	made.Anthony	VanLeuwenhoek	14	Now	that	we	are	seeing	at	the	level	of	a	cell,	we	can	imagine	what	avirus	would	"see."	Viruses	have	one	big	goal.Viruses	want	to	make	more	copies	of	themselves,	but	they	don't	havethe	tools	to	do	this	alone.	The	virus	needs	to	use	the	machinery	inside	of	your	cells.	15	Viruses	have	a	sneaky	way	of	gaining	access	to	your	cells.The	different	proteins	on	the	coat	allow	the	virus	to	virus	todock	onto	receptors	on	your	cells.The	viruses	can	then	push	the	DNA	or	RNA	into	your	cellThe	virus	docksonto	the	receptor.The	DNA	(or	RNA)	ispushed	into	your	cell!	16	But	the	virus	doesn't	stop	there,	The	virus	forces	your	cell	to	makemore	copies	of	its	DNA	or	RNA.	DNA,	proteins,	RNA,	and	lipidsCell	(and	virus)	building	blocksWe've	been	throwing	these	words	around	a	lotto	describe	viruses.	But	what	exactly	are	they?DNA:		if	you	think	of	cells	as	little	livingfactories,	you	can	think	of	DNA	as	theinstruction	manual.	It	is	a	very	long	string	ofindividual	units	called	nucleotides.	When	readout,	it	tells	the	cell	how	to	produce	what	itneeds	to	survive.	Proteins:	proteins	are	the	extremely	tinymachines	inside	of	cells.	DNA	tells	the	cellswhat	proteins	to	make	when.	Proteins	doalmost	all	of	the	work	that	keeps	us	alive,	fromforming	highways	in	our	cells	to	transportthings	to	acting	as	molecular	scissors	tountangle	DNA.	There	are	proteins	that	look	andact	like	keyboards,	recycling	bins,	and	evenwheels.	Proteins	are	made	up	of	very	longstrings	of	units	called	amino	acids.	RNA:	as	the	name	suggests,	RNA	is	verysimilar	to	DNA.	It	is	often	used	as	a	disposablecopy	of	certain	parts	of	the	DNA	manual,	butsome	viruses	carry	all	of	their	instructions	asRNA	rather	than	DNA.	Lipids:	lipids	are	fats.	They	include	things	likeoils	and	wax.	Lipids	play	important	structuralroles,	helping	to	make	up	the	coat	that	holdscells	and	viruses	together.	There	is	a	more	great	information	on	thesebuilding	blocks	in	online	educationalresources.	Check	them	out!The	DNA	(or	RNA)	is	copied,	orreplicated,	in	your	cell!	17	The	DNA	(or	RNA)	your	cell	has	just	made	for	thevirus	is	like	an	instruction	manual.	When	read	by	your	cell,	it	tells	your	cell	to	make	theproteins	that	make	up	the	viral	coat.	The	virus	has	turned	your	cell	into	a	little	factory	to	duplicate	itself!	Viral	proteins... ...assemble	into	a	new	virus!	18	and	again...and	again...This	processrepeats	again...The	viruses	can	then	infect	nearby	cells.Once	made,	the	new	viruses	burst	out	of	your	cells,which	can	hurt	your	cells.Duplicated	viruses	readyto	leave	the	cell.This	healthy	cell	is	aboutto	be	infected	by	one	ofthe	duplicated	viruses!	19	...until	it	makes	you	sick!When	a	virus	has	infected	you,	you	might	get:	All	of	these	feelings,	calledsymptoms,	are	caused	by	thevirus	infecting	your	cells.	A	runny	nose	A	sore	throat	Fever	or	chillsA	cough	Body	achesEven	though	viruses	don't	meanto	make	you	sick,	symptoms	arecaused	by	the	viruses	using	yourcells	to	copy	themselves.	20	This	all	might	seem	scary,	but	your	body	is	ready	tofight	back	for	you.		21	Different	types	of	cells	in	your	body	can	recognizethe	virus	and	help	destroy	it.	Step	1:	an	infected	cell	displays	part	of	the	viruson	its	surface.	This	tells	cells	that	make	up	yourimmune	system	that	there	is	an	invader!Step	2:	Special	cells	that	circulate	in	your	bloodnow	know	what	the	invader	looks	like.	They	caneat	the	viruses	trying	to	infect	you!Step	3:	These	cells	candestroy	the	virus.Your	other	cells	arenow	safe	from	thevirus!Your	immune	system	is	made	upby	special	cells	and	structures	inyour	body	that	help	you	whenyou	are	sick	or	could	be	infectedby	something.		22	You	can	help	your	body	by	taking	care	of	yourself	when	you're	sick.	Drink	lots	of	water.		 Get	plenty	of	rest. Keep	things	clean.Doing	these	things	can	help	you	get	better	soon	and	help	preventfamily	and	friends	that	live	with	you	from	getting	sick	too.		23	And	the	good	news	is	you	can	stop	a	virus	using	only	two	things	foundin	your	bathroom-	soap	and	water!But	alcohol	based	hand	sanitizer	works	too	if	youaren't	near	a	sink.	How	does	this	work?		24	Soap	destroys	the	protein	and	fat	coat	of	the	virus.Without	the	coat,	the	virus	can't	infect	your	cellsanymore.Soap	breaks	down	viruses!	25	The	Centers	for	Disease	Control	(CDC)	recommends	washing	yourhands	for	twenty	seconds.	26	And	because	viruses	need	our	cells	to	make	more	copies,	you	canstop	a	virus	by	making	sure	you	don't	share	it	with	someone	elsewhen	you're	sick.	Many	types	of	viruses	can	be	spreadwhen	you	cough	or	sneeze.	27	On	page	21	we	saw	that	your	cells	can	help	getrid	of	viruses	by	showing	your	immune	systemwhat	the	virus	looks	like.	The	Value	of	Vaccination:	Howshots	keep	us	safe.	You	can	help	prevent	the	spread	ofviruses	by:Covering	your	cough	and	sneeze	withyour	elbow	Staying	home	when	sickListening	to	the	advice	of	healthprofessionalsGetting	vaccinated	against	commonviruses	(it's	not	fun	but	it	reallyhelps!)Wearing	a	mask	when	recommendedby	scientists	(like	for	covid-19).	This	is	a	lot	like	helping	the	police	find	aburglar	or	thief	by	hanging	up	wanted	posters.The	problem	is,	it	can	take	a	while	for	police	toidentify	a	burglar,	and	it	can	take	your	cells	awhile	to	display	the	virus.	But	what	if	there	was	a	way	for	your	body	toknow	what	a	specific	virus	looked	like	before	itcould	infect	you	and	make	you	sick?	This	is	exactly	how	vaccination	protects	you.Shots	contain	broken	down	parts	of	virusesthat	can’t	make	you	sick	but	can	train	yourbody	what	to	look	for	in	the	future.	This	way,	ifa	real	virus	gets	into	your	body,	your	immunesystem	is	ready	to	get	rid	of	it	right	away.	Once	a	new	virus	is	discovered,	it	can	takescientists	a	while	to	make	a	new	vaccine	that	issafe.	Vaccination	is	one	very	good	way	toeradicate	(get	rid	of)	viruses	like	poliovirus	onpage	10.	Even	though	shots	aren't	fun	to	get,	they	cankeep	you	and	your	family	from	getting	sick.The	part	of	a	virusrecognized	by	yourimmune	system	iscalled	an	antigen.	28	Doing	these	things	can	help	reduce	the	spread	of	viruses,	like	SARS-CoV-2,	and	help	life	get	back	to	normal.	All	of	us	can	help	to	endcoronavirus	and	other	sicknesses	by	understanding	what	viruses	areand	how	to	best	protect	ourselves	against	them.	29	About	 the	 illustrator:	 EmilyMorin	is	a	recent	graduate	fromDartmouth	 College	 where	 shestudied	 geography	 andeconomics.	 She	 plans	 onpursuing	 a	 career	 in	 urbanplanning	and	design.	About	 the	 author:	 HannahMargolis	 is	 a	 recent	 graduatefrom	 Dartmouth	 College	 whereshe	 studied	 biochemistry	 andglobal	 health.	 She	 currentlyworks	at	 the	National	 Institutesof	Health	and	plans	to	pursue	acareer	in	science	research.		30	What	is	avirus?Written	by	Hannah	K.	MargolisIllustrated	by	Emily	J.	Morin

What is a Virus?

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