BSC Exam (2.1) Cells and Viruses

Animal Cells

Surrounded by plasma membrane: Allows certain molecules in or out of a cell, does NOT have a cell wall

Plant Cells

Has a plasma membrane AND cell wall: Cell walls give support, Has chloroplasts (Contain Chlorophyll) and large vacuole

Why are cells small?

Cells obtain nutrients (gases, water, other molecules) from the environment through the cell membrane: High surface area, volume ratios maximize amount cell/environment interaction

Virus Overview

NOT a cell: Obligate intracellular parasite of cells: Must invade cells to replicate, all ——- have genome and structural capsid': Genome may be DNA OR DNA: Dont replicate by binary fission, but produce a large number of genomes and component parts and assemble them into intact ———-.

Viral replication cycle

Attachment, entry, uncoating, synthesis of viral products, assembly, exit. major steps always occur, some slight variation can happen

Viral structure

Always have a protective cover called a capsid (made of proteins), which has a genome of nucleic acid inside.: Some viruses have a membrane outside of capsid called an envelope, which it does not make itself, but steals from membrane from infected cell.

Virus vs bacteria (bacteria)

prokaryotic cells, always DNA, divides by binary fission.

Virus vs bacteria (Virus)

Not a cell, can be DNA or RNA, replicates by assembly