Unit 4:Cells

What does the Cell Theory state?

1. All living organisms are composed of cells. 2. The cell is the basic unit of structure and function in living organisms. 3. All cells arise from preexisting cells.

Who observed cork under a microscope and named the tiny compartments 'cells'?

Robert Hooke (1665)

Who was the first to observe living microorganisms with a single-lens microscope?

Antonie van Leeuwenhoek (1673)

What did Matthias Schleiden conclude about plants?

All plants are made of cells.

What did Theodor Schwann conclude about animals?

All animals are made of cells.

Who proposed that all cells come from other cells?

Rudolf Virchow (1855)

What theory did Lynn Margulis develop in the 1960s?

The Endosymbiotic Theory explaining the origin of mitochondria and chloroplasts.

What are the main differences between prokaryotic and eukaryotic cells?

Prokaryotes lack a true nucleus and membrane-bound organelles; eukaryotes have a true nucleus and organelles.

What type of DNA do prokaryotic cells have?

Circular DNA located in the nucleoid.

What is the function of the nucleus?

Stores genetic material (DNA) and controls cellular activities.

What do ribosomes do?

Sites of protein synthesis.

What is the difference between rough ER and smooth ER?

Rough ER has ribosomes and produces proteins; smooth ER synthesizes lipids and detoxifies poisons.

What is the function of the Golgi apparatus?

Modifies, sorts, and packages proteins and lipids into vesicles.

What do lysosomes contain and what is their function?

Contain digestive enzymes to break down waste and worn-out organelles.

What is the primary function of vacuoles?

Store water, ions, nutrients, and waste.

What is the role of mitochondria in the cell?

Perform cellular respiration to produce ATP.

What is the function of chloroplasts?

Site of photosynthesis in plant cells.

What is the structure of the cell membrane?

A phospholipid bilayer with hydrophilic heads and hydrophobic tails.

What is passive transport?

Movement of materials across a cell membrane without energy, including diffusion and osmosis.

What is active transport?

Movement of materials against the concentration gradient, requiring ATP.

What is the difference between endocytosis and exocytosis?

Endocytosis is when the cell engulfs material; exocytosis is when a vesicle releases material outside the cell.

What are the main differences between plant and animal cells?

Plant cells have a cell wall, chloroplasts, and a large central vacuole; animal cells have lysosomes and centrioles.

What evidence supports the Endosymbiotic Theory?

Mitochondria and chloroplasts have their own circular DNA, 70S ribosomes, double membranes, and can replicate independently.

What is the function of the cytoskeleton?

Provides shape and movement within the cell.

What are cilia and flagella used for?

Cilia are short structures for movement; flagella are long, tail-like structures.

What is the smallest unit of life?

Cells

Who observed cork cells and named them?

Robert Hooke

What did Anton van Leeuwenhoek contribute to cell biology?

He was the first to observe living cells and invented the first single-lens microscope.

What is the function of the nucleus in a cell?

It contains the cell's DNA and is where instructions for proteins are transcribed into mRNA.

What is the role of the nucleolus?

It produces ribosomal RNA (rRNA) which combines with proteins to form ribosomes.

What is the function of the endoplasmic reticulum (ER)?

It modifies and folds proteins made by ribosomes.

What is the Golgi apparatus responsible for?

Processing, sorting, and packaging proteins into vesicles.

What are lysosomes?

Digestive organelles that break down waste.

What is the cytoskeleton's role in a cell?

It supports the internal structure and acts as a track for vesicle transport.

What is the function of mitochondria?

They provide energy (ATP) through cellular respiration.

What is a concentration gradient?

The difference in the concentration of a substance across a space, such as a cell membrane.

What is osmosis?

The diffusion of water across a cell membrane.

What happens in an isotonic solution?

The solute concentration outside the cell is the same as inside; no net water movement.

What occurs in a hypertonic solution?

The cell loses water and shrinks because the solute concentration outside is greater.

What is a hypotonic solution?

The cell gains water and swells because the solute concentration outside is less.

What is turgor pressure?

The pressure of the cell membrane against the cell wall in plant cells.

What is plasmolysis?

The loss of turgor pressure in plant cells due to water loss.

What is the fluid mosaic model?

It describes the cell membrane as a fluid structure with a mosaic of various proteins embedded in it.

What are integral proteins?

Proteins that are permanently embedded within the cell membrane's lipid bilayer.

What are peripheral proteins?

Proteins that are loosely attached to the surface of the cell membrane.

What is the sodium-potassium pump?

A cell pump that requires energy to move sodium out and potassium into the cell against their concentration gradients.

What is exocytosis?

The process of releasing substances to the outside of the cell by vesicles fusing with the cell membrane.

What is endocytosis?

The process of moving substances into the cell by forming a vesicle from the cell membrane.

What is pinocytosis?

The endocytosis of liquids.

What is phagocytosis?

The endocytosis of solids or whole cells.

What is homeostasis?

The maintenance of stable internal conditions in a changing environment.

What is the lipid bilayer?

A double layer of phospholipids that forms the cell membrane, with hydrophobic tails inside and hydrophilic heads outside.

Who proposed that all plants are made of cells?

Matthias Schleiden

Who proposed that all animals are made of cells?

Theodor Schwann

What did Robert Brown discover in plant cells?

He was the first to see a nucleus.

What did Rudolf Virchow propose about cells?

All cells come from other (pre-existing) cells.

What are the three main components of cell theory?

1. All living things are made of one or more cells. 2. Cells are the basic unit of structure and function in an organism. 3. Cells only come from the reproduction of other living cells.

What additional components are included in modern cell theory?

1. Energy flow occurs within cells. 2. Hereditary information (DNA) is passed on from cell to cell. 3. All cells have the same basic chemical composition.

What limits the size of cells?

A cell's surface area-to-volume ratio.

What are the two main types of cells?

Eukaryotes and Prokaryotes.

What is the function of the cell membrane?

It is the outer boundary of the cell that allows nutrients and wastes in and out.

What does it mean for a cell membrane to be selectively permeable?

Only some materials are allowed to pass through it.

What is the cytoplasm?

The gelatin-like aqueous fluid (cytosol) and the organelles suspended in it.

What is the role of the nucleus in a cell?

It directs all cell activities, cell division, and the making of proteins.

What is the function of ribosomes?

They make proteins.

What is the difference between Rough E.R. and Smooth E.R.?

Rough E.R. is covered with ribosomes and aids in protein synthesis, while Smooth E.R. is not covered with ribosomes and makes steroids and breaks down toxins.

What is the primary function of mitochondria?

They produce ATP by breaking down food in cellular respiration.

What do lysosomes contain?

Enzymes that digest old macromolecules like proteins, DNA/RNA, and old organelles.

What is the cytoskeleton?

A web of protein fibers that supports the cell and its organelles.

What is the function of centrioles?

They help the cell divide.

What is the cell wall and where is it found?

A rigid, inorganic layer surrounding the cell membrane found in plant cells.

What are chloroplasts responsible for?

They absorb sunlight and convert it to food through photosynthesis.

What is differentiation in multicellular organisms?

The process by which cells develop specialized forms and functions.

What are the levels of organization in multicellular eukaryotic organisms?

Cells → Tissues → Organs → Organ Systems → Organism.

What is a unicellular organism?

An organism whose entire body is made up of one cell.

What is a colonial organism?

Cells that live as a connected group but do not depend on each other for survival.

What is a multicellular organism?

An organism made up of many specialized cells that perform specific functions.