Biology Chapter 4 & 5

Who was Anton van Leeuwenhoek?

- A Dutch lens grinder (microscope maker) - He was the first person to observe living single-celled organisms in 1673 - He observed them through a rather simple microscope - He had a more powerful microscope - He mainly studied microscopic organisms - He discovered microscopic organisms

Who was Robert Hooke?

- English scientist - Looked at pieces of cork - Saw holes in the cork and discovered that those are dead cells left behind - There were living cells there before the holes - Found what he described to be " a great many little boxes" on a cork through a microscope in 1665 - Called them cells - He mostly studied plant cells - All of his research is on plants - Cells are perforated and porous (they have holes) - He made the word "Cell" - He observed DEAD plant cells - Found that elder trees, carrots, and ferns looked similar under the microscope

What are the three parts of the cell theory?

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

What are the two ways membrane proteins move materials across the cell membrane?

1. The proteins have channels or pores which are openings in which certain material can pass 2. Some proteins can attach or bind to materials and transport or carry them from one side of the membrane to the other

How many types of proteins are in the cell membrane?

2 types

Explain the difference between a unicellular organism and a multicellular organism.

A unicellular is made up of only ONE cell. A multicellular organism is made up of MULTIPLE cells. They both are equally organized, but is more complex than the other; the big difference is that one is only one cell and the other is made up of more than one cell.

What do all cells have to do?

All cells must take in nutrients and other materials ad dispose if the wastes they produce. Therefore, both nutrients and wastes must pass through the cell membrane.

How are multicellular organisms organized?

Cells are organized into tissues (Groups of cells that carry out a specific function, like lung tissue). Tissues are organized into organs (Several types of tissues that interact to perform a specific function, like the lung). Organs are organized into organ systems (A groups of organs that work together to perform a set of related tasks, like the respiratory system). Organ systems are organized into organisms.

Funtion of the cell membrane?

Controls what passes into and out of the cell; it is selectively permeable. Selectively permeable. Has proteins embedded within it that help transport materials in and out of the cell.

What are two other examples of active transport examples?

Endocytosis and Exocytosis

What is the end of diffusion called?

Equilibrium

Function of chromatin?

Inside the nuclear envelope and are fine strands. A combination of proteins and DNA. When the cell is about to divide, these strands coil up and become densely packed, forming chromosomes.

What are ion channels?

It is a type of passive transport. Each ion channel is specific for one type of ion. The ions pass in and out of the cell following the concentration gradient. Some channels are always open and others have gates.

What is facilitated diffusion?

It is a type of passive transport. It's used for molecules not soluble in lipids or too large to fit through the cell membrane

What is active transport?

It is when the cell requires to expand energy. Cells move materials AGAINST the concentration gradient, from an area of low concentration to high concentration

What can pass through the cell membrane easily?

Lipids and small items

Explain the diffusion across a membrane.

Membranes are selectively permeable. The ability to pass through the plasma membrane depends on the size and type of molecule. 1. Molecules that can dissolve in lipids may pass through the membrane by diffusion 2. Molecules that are very small but not soluble in lipids may diffuse across the membrane through the pores

What does the cell membrane act like?

More like a fluid not a solid

Why is it called a fluid mosaic model?

Mosaic means pattern....The pattern of the proteins embedded in the membrane is constantly changing

Is the cell membrane rigid?

No it is NOT rigid

What is an example of active transport?

One example of active transport in animal cells involves a carrier protein called The Sodium-Potassium Pump. To function normally, many types of animal cells must have a higher concentration of Na+ ions outside the cell and a higher concentrations of K+ ions inside the cell

Explain the two types of proteins in the cell membrane.

Peripheral Proteins: Located on the surfaces of the cell membrane (Floating-DOESN'T go inside the layer of the cell membrane) Integral Proteins: Proteins that are embedded in the bi-layer (DOES go inside the layer of the cell membrane)

What kinds of endocytosis are there? Explain them.

Pinocytosis involves the taking in of solutes and fluids Phagocytosis involves the taking in of large particles

What are the differences between plant and animal cells?

Plant Cell: -Large vacuole - Chloroplasts - Cell wall - Rectangular in shape Animal Cell: -Many smaller vacuoles -Centrosomes (2 centrioles) -Round in shape Both: - Plasma membrane - Mitochondria - Smooth and rough endoplasmic reticulum - Contains DNA (Genetic Material) - Undergo cell division and reproduction - Golgi apparatus

Describe the difference between a prokaryotic cell and a eukaryotic cell?

Prokaryote: - No nucleus - No membrane- bound organelles - Most 1-10 units in size - Evolved 3.5 billion years ago - Only bacteria Eukaryote: - Nucleus - Many organelles - Many 2-1,000 units in size - Evolved 1.5 billions years ago - All other cells

Function of the cilia and flagella?

Propels the cells through the environment; move materials over the cell surface. They are hairlike organelles that extend from the surface of the cell and assist in movement of the cell. Cilia is many organelles. Flagella is one organelle. Not all cells have these.

What makes up the cell membrane?

Proteins and Lipids

Function of the cytoplasm?

Region of the cell outside the nucleus and inside the plasma membrane, contains the organelles

Function of nucleolus?

Ribosomes are synthesized and partially assembled here

Function of the endoplasmic reticulum?

Rough Endoplasmic Reticulum: Covered in ribosomes, it is an intracellular highway along which molecules move from one part of the cell to another Smooth Endoplasmic Reticulum: Smooth when you look at it (No ribosomes on it). Has a part in protein production. It is involved in the synthesis of steroids in gland cells, the regulation of calcium levels in muscle cells, and the breakdown of toxic substances by liver cells

Function of the ribosomes?

Some are free an others are attached on the endoplasmic reticulum. Play an important role in protein synthesis.

Why do endocytosis and exocytosis occur?

Some substances, such as macromolecules and food particles are too large to pass through the cell membrane by the other transport processes. Endocytosis and Exocytosis are used to transport large quantities of small molecules or large substances across the cell membrane. They require the cell to acquire energy and are therefore types of active transport.

Function of the vacuole?

Stores enzymes and waste products. Usually quite large in plants, they often store enzymes and waste products.

Function of the plastid?

Stores food or pigments; one type is the chloroplast. Surrounded by two membranes and contain DNA

Function of the nucleus?

Stores hereditary information in DNA; synthesizes RNA and ribosomes. Heredity information is stored here.

Function of the chloroplasts?

Sunlight is converted into chemical energy within this organelle

Function of the cell wall?

Supports and protects the cell. Only found in plant cells, they often store enzymes and wastes.

What do the carrier proteins do in an active transport?

The carrier proteins that assist in passive transport also help with some types of active transport. The carrier proteins that help in active transport are often called cell membrane "pump"

What is the cell membrane considered?

The cell membrane is called "selectively permeable" which means some substances can easily cross the membrane but others cannot

What is a concentration gradient?

The difference in the concentration of molecules across a space. When the concentration is equal, there is no more concentration gradient

What is diffusion?

The movement of molecules from an area of high concentration to low concentration. It is natural and it is a form of passive transport.

What is a passive transport?

The movement of substances across the cell membrane without any energy input from the cell

What is Endocyctosis?

The process by which cells ingest external fluids or large particles

What is osmosis?

The process by which water molecules diffuse across a cell membrane from an area of higher concentration to an area of lower concentration. It is natural and a form of diffusion, but diffusion is NOT always osmosis

What limits cell size?

The ratio between their outer surface area and their volume

Explain the Phospholipid Bi-Layer.

Their are two layers of lipids. The outer part of the cell membrane is a line of glycerol. They love water, so the outside and inside of the cell is hydrophillic, or water loving. The inside part of the cell membrane are the fatty acid chains off of the glycerol. They hate water, so the inside of the cell is hydrophobic, or water fearing. The glycerol and fatty acid chain together is called a phospholipid. That is why the cell membrane is called the phospholipid bi-layer.

What are carrier proteins?

They assist these kinds of molecules across the membrane

Why are cells different shapes?

They come in a variety of different shapes because the shape reflects a diversity of function

Function of the microfilaments and microtubules?

They contribute to the support, movement, and division of cells. Microtubles: Found in both plant and animal cells, they provide support to the structure of the cell. They are the largest strands of the cytoskeleton that are hollow tubes. Microfilaments: Threads made of a protein called actin. They constitute the smallest strands that make up the cytoskeleton

What did scientists discover about the cell membrane?

They discovered that cell membranes are dynamic or they change. Membrane proteins are free to move to where they are needed.

What do membrane proteins help?

They help materials get across the cell membrane in two ways

Function of the lysosome?

This structure digests organic molecules, old organelles, viruses and bacteria

Function of the mitochondria?

This structure transfers energy from organic compounds to ATP (cell fuel). It has a double membrane structure. The inner membrane has many long folds called cristae. This organelle has it's own DNA and only when this organelle grows and divides are new ones produced.

What can the cell membrane control?

What substances can pass into or out of the cell

Function of the Golgi apparatus?

Works with E.R. It processes and packages substances produced in the cell

Is facilitated diffusion still a form of passive transport?

Yes because the molecules are still moving down the concentration gradient (high to low), so it is still considered a form of passive transport