Cell structure

What are the three main principles of cell theory?

All living things are made of cells.Cells are the smallest units of life capable of survival. All cells come from pre-existing cells

Which scientist disproved spontaneous generation?

Louis Pasteur

What are the two main types of microscopes?

Light microscopes and electron microscopes.

What is the main difference between TEM and SEM?

SEM shows surface, TEM shows internal structures

What does freeze-fracture electron microscopy help study?

The structure of cell membranes

In cryogenic electron microscopy, proteins are frozen using ____ and viewed from multiple angles to form a 3D structure.

Ethane.

Why are fluorescent stains useful?

They bind to specific cellular components and make them visible under a fluorescence microscope.

Immunofluorescence links ________ to fluorescent stains to target specific ________.

Antibodies. Antigens

List the seven functions of life

Metabolism, replication, movement, excretion, response, growth, nutrition, homeostasis.

Which of the following is NOT a function of life?

Digestion

What structures are present in all cells?

Plasma membrane, DNA, cytoplasm, ribosomes.

Ribosome size in prokaryotes is

70s

Which structure allows bacterial cells to exchange genetic material?

Pili

What is the function of the slime capsule in some prokaryotes?

Protection against dehydration and phagocytosis.

Which cell type has mitochondria?

Only eukaryotes

What is the function of amyloplasts?

Storage of starch.

Why do red blood cells lack a nucleus and mitochondria?

To maximize space for hemoglobin and increase oxygen-carrying efficiency.

Which cell type is multinucleated and results from the fusion of many cells?

Skeletal muscle cells

What makes aseptate fungal hyphae unique?

They form long, multinucleated filaments without distinct cell boundaries.

What is endosymbiosis?

A symbiotic relationship where one cell lives inside another for mutual benefit.

Which organelles originated from endosymbiotic bacteria?

Mitochondria and chloroplasts.

Evidence for the endosymbiotic theory includes all EXCEPT:

80S ribosomes

What is symbiosis?

two different organisms living together

What is cell differentiation?

The process where cells express certain genes and specialize for specific functions.

What are stem cells?

Undifferentiated cells that can develop into any cell type.

Gene expression can be influenced by external factors such as

Temp, light, chemicals, or drugs.

Why is cell specialization beneficial?

Increases efficiency, Allows energy saving, Enables evolution of specialized functions

What are the two steps in the evolution of multicellularity?

Formation of cellular clusters. Differentiation of cells for specialized functions.

Which of the following hypotheses explains the evolution of multicellularity?

Cells failed to separate after mitosis