Biology: Cells, Viruses, and Basic Life Concepts

Flashcards covering core concepts from cell biology, cell types, organelles, metabolism and homeostasis, growth and development, reproduction, adaptation/evolution, DNA, and viruses (including replication cycles and distinctions between viruses and living cells).

What is the basic unit of life that all living things are composed of?

Cells (one or more per organism).

What are the two main categories of cells?

Prokaryotic and eukaryotic cells.

What characterizes prokaryotic cells?

They lack a nucleus and membrane-bound organelles.

What characterizes eukaryotic cells?

They have a nucleus and membrane-bound organelles.

Which organisms have prokaryotic cells?

Bacteria and archaea.

Which organisms have eukaryotic cells?

Protists, plants, animals, and fungi (unicellular or multicellular).

What is the function of mitochondria?

Powerhouse of the cell; produces energy (ATP) from glucose.

What is the function of ribosomes?

Synthesize proteins.

What is the function of the endoplasmic reticulum?

A network of membranes involved in protein and lipid synthesis and transport.

What is the function of the Golgi apparatus?

Packages and ships proteins and lipids within the cell and for secretion.

What is the nucleus and what does it contain?

The nucleus contains the cell's DNA and controls activities.

Do all cells have a cell wall?

Most prokaryotic cells have cell walls; many eukaryotic cells (plants, fungi) have cell walls; animal cells usually do not.

What is homeostasis?

Maintenance of a stable internal environment (constant temperature, pH, energy supply).

What is metabolism?

All chemical reactions and energy transformations in an organism.

How do organisms grow and develop?

Growth is an increase in size or cell number; development is maturation and changes in form/function.

What is reproduction?

The production of new organisms; can be asexual (cloning) or sexual (involving fertilization).

What is adaptation in evolution?

Inherited traits that improve survival in a given environment; populations evolve over time via natural selection.

What are the four key observations of natural selection?

Variation among individuals; overproduction of offspring; competition for limited resources; differential survival and reproduction.

What is DNA?

The molecule that carries genetic information; blueprint for proteins.

What is a virus?

A non-cellular infectious agent that requires a host to replicate; contains genetic material (DNA or RNA) and a protein coat (capsid); may have an envelope; not a cell.

What are the two main viral replication cycles?

The lytic cycle and the lysogenic cycle.

How does the lysogenic cycle differ from the lytic cycle?

In lysogeny, viral DNA integrates into the host genome and replicates with it; in the lytic cycle, the virus rapidly replicates and lyses the host cell.

What is a bacteriophage?

A virus that infects bacteria.

Why are viruses often host-specific?

Viruses tend to infect specific host species or cell types because they require particular receptors and cellular machinery.

What is phototropism?

A plant's growth response toward light.

Give an example of asexual reproduction in plants.

Strawberries reproducing via runners to form genetically identical daughter plants.

What is amoeboid movement?

Movement by extending and retracting cytoplasmic projections called pseudopods.

What does sessile mean?

Attached to a surface and not freely movable; fixed in place.

What are sex chromosomes in humans and how do they differ by sex?

Females typically have two X chromosomes; males have one X and one Y; the Y chromosome is smaller and shrinking.