Biology Chapter 3

List three structures that are found in plant cells but not in animal cells.

Plant cells have several structures that are not found in animal cells, including a cell wall, a large central vacuole, and organelles called plastids.

prokaryotic cells.

Prokaryotic cells are cells without a nucleus. The DNA in prokaryotic cells is in the cytoplasm rather than enclosed within a nuclear membrane. Prokaryotic cells are found in single-celled organisms, such as bacteria

Exocytosis

he type of vesicle transport that moves a substance out of the cell. A vesicle containing the substance moves through the cytoplasm to the cell membrane. Then, the vesicle membrane fuses with the cell membrane, and the substance is released outside the cell. You can watch an animation of exocytosis at the link below.

Endocytosis

he type of vesicle transport that moves a substance into the cell. The plasma membrane completely engulfs the substance, a vesicle pinches off from the membrane, and the vesicle carries the substance into the cell. When an entire cell is engulfed, the process is called phagocytosis. When fluid is engulfed, the process is called pinocytosis.

List functions of the cytoplasm.

1. suspending cell organelles 2. pushing against the plasma membrane to help the cell keep its shape 3. providing a site for many of the biochemical reactions of the cell

Outline the levels of organization of cells in living things, starting with the simplest level, that of single-celled organisms.

A single-celled organism floats freely and lives independently. Its single cell is able to carry out all the processes of life without any help from other cells. • A biofilm is a thin layer of bacteria that sticks to a surface. Cells in a biofilm are all alike, but they may play different roles, such as taking in nutrients or making the "glue" that sticks the biofilm to the surface. The sticky plaque that forms on teeth is a biofilm of bacterial cells. • Some single-celled organisms, such as algae, live in colonies. A colony is an organized structure composed of many cells, like the Volvox sphere in Figure 3.21. Volvox are algae that live in colonies of hundreds of cells. All of the cells in the colony live and work cooperatively. For example, they can coordinate the movement of their flagella, allowing them to swim together through the water as though they were part of a single organism. • A multicellular organism consists of many cells and has different types of cells that are specialized for various functions. All the cells work together and depend on each other to carry out the life processes of the organism. Individual cells are unable to survive on their own.

State the cell theory.

All organisms are made of one or more cells. All the life functions of organisms occur within cells. All cells come from already existing cells.

What Discoveries lead to the cell theory.

By the early 1800s, scientists had observed the cells of many different organisms. These observations led two German scientists, named Theodor Schwann and Matthias Jakob Schleiden, to propose that cells are the basic building blocks of all living things. Around 1850, a German doctor named Rudolf Virchow was studying cells under a microscope when he happened to see them dividing and forming new cells. He realized that living cells produce new cells through division. Based on this realization, Virchow proposed that living cells arise only from other living cells. The ideas of all three scientists—Schwann, Schleiden, and Virchow—led to the cell theory, which is one of the fundamental theories of biology

Describe the roles of transport proteins in cell transport.

Carrier proteins bind with specific ions or molecules, and in doing so, they change shape. As carrier proteins change shape, they carry the ions or molecules across the membrane.

Describe the Diversity of cell shapes.

Cells with different functions generally have different shapes that suit them for their particular job. Cells vary in size as well as shape, but all cells are very small. In fact, most cells are much smaller than the period at the end of this sentence.

eukaryotic cells

Eukaryotic cells are cells that contain a nucleus.Eukaryotic cells are usually larger than prokaryotic cells, and they are found mainly in multicellular organisms. Organisms with eukaryotic cells are called eukaryotes, and they range from fungi to people. Eukaryotic cells also contain other organelles besides the nucleus.

List functions of the cytoskeleton.

It helps the cell maintain its shape and also holds cell organelles in place within the cytoplasm.

What is osmosis? What type of transport is it?

Osmosis is a special type of diffusion — the diffusion of water molecules across a membrane. Like other molecules, water moves from an area of higher concentration to an area of lower concentration. Water moves in or out of a cell until its concentration is the same on both sides of the plasma membrane.

Name the three scientists mainly responsible for developing the cell theory.

Schwann, Schleiden, and Virchow

What is endosymbiotic theory? How does it explain the presence of certain organelles in eukaryotic cells?

Scientists think that mitochondria were once free-living organisms because they contain their own DNA. They theorize that ancient prokaryotes infected (or were engulfed by) larger prokaryotic cells, and the two organisms evolved a symbiotic relationship that benefited both of them. The larger cells provided the smaller prokaryotes with a place to live. In return, the larger cells got extra energy from the smaller prokaryotes. Eventually, the prokaryotes became permanent guests of the larger cells, as organelles inside them. This theory is called the endosymbiotic theory, and it is widely accepted by biologists today

Describe different types of passive transport.

Simple Diffusion, Osmosis, Facilitated Diffusion

What is the sodium-potassium pump?

Sodium Potassium Pump-When this pump is in operation, sodium ions are pumped out of the cell, and potassium ions are pumped into the cell. Both ions move from areas of lower to higher concentration, so ATP is needed to provide energy for this "uphill" process.

What is the role of the nucleus of a eukaryotic cell?

The nucleus controls which proteins the cell makes. The nucleus of a eukaryotic cell contains most of the cell's DNA, which makes up chromosomes and is encoded with genetic instructions for making proteins.

Identify the parts that all cells have in common.

The parts include a plasma membrane, cytoplasm, ribosomes, and DNA.

Describe the composition of the plasma membrane.

The plasma membrane is composed mainly of phospholipids, which consist of fatty acids and alcohol. The phospholipids in the plasma membrane are arranged in two layers, called a phospholipid bilayer.

Explain why cells are small.

To carry out life processes, a cell must be able to quickly pass substances into and out of the cell. For example, it must be able to pass nutrients and oxygen into the cell and waste products out of the cell.

What did Hooke and Leeuwenhoek discover about cells by using a microscope?

hooke was still able to make an important discovery. When he looked at a thin slice of cork under his microscope, he was surprised to see what looked like a honeycomb.Leeuwenhoek made his own microscope lenses, and he was so good at it that his microscope was more powerful than other microscopes of his day. In fact, Leeuwenhoek's microscope was almost as strong as modern light microscopes. Using his microscope, Leeuwenhoek discovered tiny animals such as rotifers.