biology chapter 1

What did Robert Hooke discover?

He looked at cork under a microscope and called the small empty spaces “cells.”

Why could Robert Hooke not see nuclei or organelles?

He was looking at dead cork tissue.

Who was the first person to view a living cell under a microscope?

Anton van Leeuwenhoek.

What are the four tenets of cell theory?

All living things are made of cells; the cell is the basic unit of life; cells come from preexisting cells; cells carry DNA passed to daughter cells.

What is the basic functional unit of life?

The cell.

Why do viruses create a problem for cell theory?

They have genetic material but are not cells and cannot reproduce on their own.

Are viruses considered living organisms?

No, because they are acellular and depend on host cells.

What does acellular mean?

Not made of cells.

What is the main difference between prokaryotic and eukaryotic cells?

Eukaryotes have a nucleus and membrane-bound organelles; prokaryotes do not.

What are prokaryotic cells?

Cells with no true nucleus and no membrane-bound organelles.

Where is prokaryotic DNA located?

In the nucleoid region.

What are eukaryotic cells?

Cells with a true nucleus and membrane-bound organelles.

What is compartmentalization?

Separating cell functions into different organelles.

Why is compartmentalization helpful?

It lets different reactions happen in separate areas with more control and efficiency.

What is the cytosol?

The semiliquid fluid inside the cell where organelles are suspended.

What is a phospholipid bilayer?

A double layer of phospholipids that forms cell and organelle membranes.

What part of a phospholipid is hydrophilic?

The head.

What part of a phospholipid is hydrophobic?

The tails.

Why do membranes matter?

They separate spaces, control what enters and leaves, and help maintain different environments.

What is the nucleus?

The control center of the cell that stores DNA and is the site of transcription.

What surrounds the nucleus?

The nuclear envelope, also called the nuclear membrane.

Is the nuclear envelope single or double membrane?

Double membrane.

What do nuclear pores do?

They allow selective two-way exchange between the nucleus and cytoplasm.

What can pass through nuclear pores?

RNA, ribosomal subunits, proteins, and nucleotides.

What are histones?

Proteins that eukaryotic DNA wraps around for organization.

What are chromosomes?

DNA and proteins packed into organized structures.

What are genes?

Coding regions of DNA.

Why is the nucleus important for gene expression?

It separates transcription in the nucleus from translation in the cytoplasm.

What is the nucleolus?

A dark region inside the nucleus that makes ribosomal RNA.

What does the nucleolus make?

rRNA.

What are mitochondria known as?

The powerhouse of the cell.

What is the main function of mitochondria?

To produce ATP through oxidative phosphorylation.

How many membranes do mitochondria have?

Two membranes: outer membrane and inner membrane.

What does the outer mitochondrial membrane do?

It separates the mitochondrion from the cytosol.

What are cristae?

Folds of the inner mitochondrial membrane.

Why are cristae important?

They increase surface area for electron transport chain enzymes.

What is the intermembrane space?

The space between the outer and inner mitochondrial membranes.

What is the mitochondrial matrix?

The space inside the inner mitochondrial membrane.

What happens during oxidative phosphorylation?

Protons are pumped into the intermembrane space and flow through ATP synthase to make ATP.

What is special about mitochondrial DNA?

Mitochondria have their own DNA.

How do mitochondria divide?

By binary fission.

What theory explains the origin of mitochondria?

Serial endosymbiosis theory.

What is cytoplasmic inheritance?

Inheritance of genetic material from organelles outside the nucleus, like mitochondria.

What is apoptosis?

Programmed cell death.

How are mitochondria involved in apoptosis?

They can release enzymes that start programmed cell death.

What are lysosomes?

Membrane-bound organelles with hydrolytic enzymes.

What is the main function of lysosomes?

To digest and break down materials.

What can lysosomes break down?

Cell waste, old organelles, materials from endocytosis, and biological molecules.

What are endosomes?

Vesicles involved in transporting and sorting materials inside the cell.

Where can endosomes send material?

To the Golgi, cell membrane, or lysosomes.

What is autolysis?

Self-digestion of the cell caused by lysosomal enzymes.

What is the endoplasmic reticulum?

A series of interconnected membranes continuous with the nuclear envelope.

What are the two types of ER?

Rough ER and smooth ER.

Why is rough ER called rough?

It has ribosomes attached to it.

What is the main function of rough ER?

Protein synthesis for proteins that will be secreted or inserted into membranes.

Where do proteins from rough ER usually go next?

To the Golgi apparatus for modification and packaging.

Does smooth ER have ribosomes?

No.

What are the main functions of smooth ER?

Lipid synthesis, detoxification, and transport of proteins from rough ER to Golgi.

What does smooth ER synthesize?

Lipids, including phospholipids and steroids.

What organelle detoxifies drugs and poisons?

Smooth ER.

What is the Golgi apparatus?

Stacked membrane-bound sacs that modify, package, and sort cellular products.

What does the Golgi apparatus add to materials?

Groups such as carbohydrates, phosphates, and sulfates.

What does the Golgi package products into?

Vesicles.

Where can Golgi vesicles send products?

Lysosomes, cell membrane, secretory vesicles, or outside the cell.

What is exocytosis?

When a vesicle fuses with the plasma membrane and releases contents outside the cell.

What are peroxisomes?

Single membrane-bound organelles containing hydrogen peroxide.

What are peroxisomes important for?

Breaking down very long chain fatty acids, lipid synthesis, and parts of the pentose phosphate pathway.

What would happen if peroxisomes could not make hydrogen peroxide?

They could not properly break down very long chain fatty acids.

What is the cytoskeleton?

A network of proteins that gives the cell shape, support, and transport pathways.

What are the three parts of the cytoskeleton?

Microfilaments, microtubules, and intermediate filaments.

What are microfilaments made of?

Actin.

What do microfilaments do?

Help with cell shape, movement, and cleavage furrow formation.

What motor protein works with actin?

Myosin.

What are microtubules made of?

Tubulin.

What do microtubules do?

Help with vesicle transport, cilia, flagella, centrioles, and chromosome movement.

What motor proteins move along microtubules?

Kinesin and dynein.

What is a centrosome?

The region of the cell where centrioles are found.

What is a centriole?

A hollow structure made of nine triplets of microtubules.

What do centrioles do?

Organize microtubules and help separate chromosomes during mitosis.

What are intermediate filaments made of?

Proteins such as keratin, desmin, vimentin, and lamins.

What do intermediate filaments do?

Provide strength, withstand tension, anchor organelles, and help cell-cell adhesion.

What are cilia?

Projections that move materials along the cell surface.

What are flagella?

Structures that move the cell itself.

What is the structure of eukaryotic cilia and flagella?

9 + 2 arrangement of microtubules.

How are centrioles different from eukaryotic flagella?

Centrioles have nine triplets; eukaryotic flagella have 9 + 2 microtubules.

What are the four tissue types?

Epithelial, connective, muscle, and nervous tissue.

What is epithelial tissue?

Tissue that covers the body and lines cavities.

What do epithelial tissues help with?

Protection, absorption, secretion, and sensation.

What does it mean that epithelial cells are polarized?

One side faces the lumen or outside world, and the other side attaches to underlying tissue.

What is a lumen?

The inside space of a hollow tube or organ.

What is the basement membrane?

A layer of connective tissue that epithelial cells attach to.

What is simple epithelium?

One layer of epithelial cells.

What is stratified epithelium?

Multiple layers of epithelial cells.

What is pseudostratified epithelium?

Cells look layered but all touch the basement membrane.

What are the three epithelial cell shapes?

Squamous, cuboidal, and columnar.

What are squamous cells?

Flat, scale-like cells.

What are cuboidal cells?

Cube-shaped cells.

What are columnar cells?

Tall, column-shaped cells.

What is connective tissue?

Tissue that supports the body and provides a framework for other tissues.

What is parenchyma?

The functional part of an organ.