Name: _________________________________________________ Date: _______________ Period: ________ Biology Notes: Viruses Directions: Fill in the blanks as we cover the topic in the PowerPoint. Corresponds to textbook pages 549 ‐ 551 What is a virus? • Virus: A biological _________________ composed of ________________________ and _______________. • Intracellular Parasites: organism that _______________ “live” inside a _________________ Are viruses alive? • YES – __________________ – Have __________________ __________________ – __________________ to surroundings – Have __________________ • NO – __________________ made of _________________ or __________________ – __________________ reproduce on __________________ – Don’t metabolize __________________ – Don’t __________________ cellular__________________ Virus Parts • All Have: – 1) Capsid: coat of ________________ that surrounds ________________________________. – 2) Nucleic Acid: _________________ or ________________ • Some Have: – Tail Fibers: Used for _____________________ (___________ legs) – Shape & size __________________ Viral Replication – Bacteriophages (__________________ that attack ________________) are often studied – Replication is __________________ with many animal viruses – Two “life” cycles: __________________ & __________________ The Lytic Cycle st
• 1 Step: Attachment •
•
•
–
Virus __________________ on cell __________________ –
Virus __________________ to a cell _______________ –
Virus acts as __________________; __________________ acts as __________________ –
No attachment = No __________________ 2nd Step: Entry –
Virus enzyme ________________ cell __________________ –
Genetic material (__________________or __________________) _______________ host cell 3rd Step: Replication –
Virus DNA/RNA uses __________________ to make ________________ proteins –
Virus ________________ created by ______________________________________________________ 4th Step: Assembly •
•
________________ virus proteins are assembled in the cell’s ________________ 5th Step: Release –
Virus enzyme causes cell membrane _________________ (burst) –
Viruses are ________________ to find new ________________ –
Cycle repeats Lysogenic Cycle: st
• 1 step: Attachment = Same as _________________ cycle •
•
Virus lands on cell membrane. Virus attaches to a cell receptor. 2nd Step: Entry = Same as _________________ cycle -
Virus enzyme weakens cell membrane -
Genetic material (DNA or RNA) enters host cell 3rd step: Replication –
_________________ created –
______________________ combines with cell _____________________ = ___________________! –
Infected cell _______________ by _______________ and copies the ________________ –
Each _______________ cell will contain the ________________ •
4th Step: Assembly: Same except, many new _______________ are assembled in _______________cells. •
5th Step: Release: Same except, many cells ________________, releasing _______________ more viruses. Review 1) Circle the correct answer to the statement: True or False All viruses have a capsid, nucleic acid, and tail fibers. 2) List 3 reasons why viruses may be living: Nonliving: 1. _______________________________________ 1. _______________________________________ 2. _______________________________________ 2. _______________________________________ 3. _______________________________________ 3. _______________________________________
3) What is the virus capsid made from? _________________________________________________________ 4) What type of organism do phages infect? _____________________________________________________ 5) In order list the stages of the lytic/lysogenic cycles: ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ 6) In which stage… - Does the host cell explode?_____________________ - Are virus proteins built to make new viruses? ______________________________________ - Is a provirus created? _________________________ - Does a virus connect with the host cell’s receptors? ______________________________ 7) Which two objects make up a provirus? ______________________________________________________ 8) Which virus “life” cycle is considered the most harmful? Why? ____________________________________ _______________________________________________________________________________________ 9) Place the following steps of the lytic cycle in order (#1 = First).