7th Science Bateria & Virus Outlines Flashcards
_______ are unicellular organism that do not have a nucleus or other membrane-bound organelles.
Prokaryotes
_______ are microscopic prokaryotes.
Bacteria
There are two types of prokaryotes - bacteria and ______.
Atchaea
A typical bacterium consists of DNA and ____ surrounded by a cell membrane and a cell wall.
cytoplasm
Bacterial cytoplasm also contain _______.
Ribosomes
Bacterial DNA occurs in one coiled, circular ________.
Chromosome
A bacterium might also have smaller, circular __________ that are separate from its other DNA.
Pieces
Many bacteria have capsules with hairlike structures called ________ that help the bacteria stick to surfaces.
Pili
Bacteria are much _______ than plant or animal cells.
Smaller
Bacteria generally have one of three basic shapes - sphere, rod, or ______.
Spiral
Some bacteria take in food and break it down and obtain _______. The food can come from dead organisms or ________ hosts.
Energy; living
Other bacteria make their food using energy from ______ or chemical reactions.
Light
________ bacteria can survive without oxygen.
Anaerobic
________ bacteria need oxygen, as humans do.
Aerobic
Many bacteria have long whiplike structures called _____ that they use for movement.
Flagella
Bacteria reproduce asexually by ________. This type of cell division forms two genetically _______ cells.
Fission; indentical
During _______, two bacteria of the same species attach to each other and combine their genetic material.
Conjugation
_______ is transferred between bacteria during conjugation.
DNA
Conjugation results in new combinations of genes and increases genetic ______.
Diversity
A(n) __________ forms when a bacterium builds a thick inner wall around its chromosome and part of the cytoplasm.
Endospores
An endospore can protect a bacterium from intense heat, cold, or ________. It can remain ________ for months or even centuries.
Drought; dormant
Like a bacterium, a(n) ________ has a cell wall but no nucleus or membrane-bound organelles.
Arachaea
The ribosomes of archaea more closely resemble the ribosomes of ________ than those of bacteria.
Eukaryotes
Archaea often live in _______ environments, such as hot springs and salt lakes.
Extreme
Many organisms, including humans, depend on ______ to survive.
Bacteria
Bacteria living inside the ______ of humans and other animals help digest food, make vitamin K, and prevent harmful bacteria from growing.
Intestines
Bacteria in the rumens of cows break down a substance in grass called _______ into smaller molecules that the cow can use.
Cellulose
__________, the breaking down of dead organisms and organic waste, is an important process in nature.
Decomposition
As bacteria and other _______ break down dead organic mater, they release molecules such as carbon and phosphorus into the soil.
Decomposers
______ is the conversion of atmospheric nitrogen into nitrogen compounds that living things can use.
Nitrogen Fixation
Bacteria is the root ______ of certain plants carry out nitrogen fixation.
Nodules
_______ uses organisms, such as bacteria, to clean up environmental pollution. These organisms break down harmful substances, such as sewage, into less harmful materials that can be used as landfill or _______.
Bioremediation: fertilizers
______ are used to make food such as pickles, yogurt, cheeses, buttermilk, vinegar, and soy sauce.
Bacteria
Some bacteria are called _______ - agents that cause disease.
Pathogens
Some pathogens that normally live in the body cause illness only when the person’s _______ system is weakened.
Immune
Some pathogens can enter the body through a cut, in air, or on _______. After they are inside the body, they can ______ and cause disease.
Food you eat; reproduce
Some bacteria make people sick by damaging ______.
Tissue
Some bacteria cause illness by releasing ________.
Toxins
_________ are medicines that stop the growth and reproduction of bacteria.
Antibiotics
Bacteria can become ________ to antibiotics.
Resistant
Random _______ to a bacterium’s DNA enable it to survive a specific antibiotic.
Mutations
Only the bacteria with the mutation survive, they ______ and become more common.
Reproduce
When bacteria become ______- to an antibiotic, a different antibiotic must be used to fight the disease.
Resistant
Eating food contaminated by some bacteria can cause ________.
Food poisoning
_______ heats food to a temperature that kills most harmful bacteria.
Pasteurization
A(n) ______is a strand of DNA or RNA surrounded by a layer of protein that can infest and replicate in a host cell.
Virus
A virus does not have a(n) ________, any other organelles, or a cell membrane.
Cell wall
Scientists do not consider viruses to be _______ because they do not have all the characteristics of a living organism.
Alive
Viruses must use ______ to carry on the processes that we usually associate with a living cell.
Organisms
The living cell that a virus infects is called a(n) ______ cell.
Host
After a virus attaches to the host cell, its DNA or ______ enters the host cell.
RNA
When a virus enters a cell, it can be ______ for years before taking over the cell.
Inactive
After a virus replicates in the host cell, it _______ the host cell. Copies of the virus are then released into the host organism, where they can _______ other cells.
Destroys; infect
As viruses replicate, their DNA or RNA frequently ______ or changes.
Mutates
As viruses change, they can produce new ways to _____ to host cells.
Attach
These changes happen so rapidly that it can be difficult to cure or prevent viral _________ before the virus mutates again.
Diseases
Viruses cause many human _______, such as chicken pox, influenza, HIV, and the common cold. Viruses can also affect other animals and _______.
Diseases; plants
Viruses such as influenza cause symptoms soon after _____. __________ viruses such as HIV might not cause symptoms right away.
Infection; latent
Viral diseases can be difficult to treat because viruses are constantly _______.
Changing
Antibodies work only against _______, not viruses.
Bacteria
One of the best ways to prevent infection is to limit _______ with an infected organism.
Contact
__________ occurs when a person is infected by a virus and then becomes immune to it.
Immunity
When a virus infects a person, the body begins to make special proteins called ________.
Antibody
An antibody is a protein that prevents a(n) ________ in the body.
Pathogen
_______ develops when a mother passes antibodies to her unborn baby.
Natural Immunity
A(n) ________ is a mixture containing material from one or more deactivated pathogens, such as viruses. It triggers the production of ______.
Vaccine; antibodies
Scientists are researching new ways to treat and ______ viral disease in humans, animals, and plants.
Preventing
Scientists are studying the link between viruses and ______.
Cancer
Viruses are being tested as treatments for genetic disorders and cancer using ______.
Gene Transfer
