Cell Structure- Chapter 2

microscope

An instrument that makes small objects look larger

light microscope

sends a beam of light through a cell, which is then focused by two lenses

electron microscope

focuses a beam of electrons through the specimen or onto its surface

Ultrastructure

refers to fine detail, down to the molecular level, revealed by the electron microscope

cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

nucleus

Control center of the cell, contains DNA

Chromosomes

threadlike structures made of DNA molecules that contain the genes

What contains the instruction for the manufacture of proteins in the cell?
What do these proteins determine?

genes, the functions of the cell

HOW does the nucleus determine the structure of the cell and its activities?

The nucleus regulates what proteins are made so it determines the structure and activities

What makes RNA (Ribonucleic acid)

A dark staining part of the nucleus, called the nucleolus

What is the cell membranes function? What is it made out of?

Cell membrane is selectively permeable, made of protein and phospholipids

Chromatin

Clusters of DNA, RNA, and proteins in the nucleus of a cell

Nucleolus

Found inside the nucleus and produces ribosomes

Mitochondria

Powerhouse of the cell- energy supply

Chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

cell wall

A rigid layer of nonliving material that surrounds the cells of plants and some other organisms.

Ribosomes

Makes proteins for the cell

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea.

Eukaryotic cells

Contain a nucleus and other organelles that are bound by membranes.

What are cell membranes made out of?

phospholipids and proteins that are in constant motion
-membranes are said to be fluid

What is the function of the cell membrane?

The cell membrane regulates what enters and leaves the cell and also protects and supports the cell.

What is the function of the nucleus?

Controls cell activities, stores DNA

What does the nucleus contain?

Contains chromosomes which have DNA (elongated non dividing chromosomes called chromatin)- genetic info.

What does DNA stand for?

deoxyribonucleic acid

Where is the nucleolus located and what is its function?

-Located in the nucleus
-makes ribosomes
-contains RNA, DNA and proteins

Draw a labelled diagram of the cell membrane

phospholipids, protein, phosphate head, pore, lipid tail, membrane

Draw a labelled diagram of the nucleus

nuclear pore, chromatin, nucleolus, double nuclear membrane, nucleoplasm

Describe the cell wall

* made of strong fibrous __cellulose__ (structural polysaccharide)
* __prevents__ it from bursting at it fills with water
* It is __fully permeable__ and has no control over the entry of substances into the cell.

What does a vacuole consist of?

* A vacuole consists of a __membrane bag__ filled with __cell sap__
* Stores sugars and salts that are dissolved in water.
* When water moves into the vacuole, it pushes the cytoplasm against the cell membrane and cell wall giving the cell turgor (turgidity)

What happens when water moves into a vacuole?

When water moves into the vacuole, it pushes the cytoplasm against the cell membrane and cell wall giving the cell turgor (turgidity)

Chromatin

Name given to chromosomes when they are elongated and not dividing

What are cell membranes made out of?

Mostly phospholipids and proteins

Why are cell membranes said to be fluid?

Because their components, phospholipids and proteins are in constant motion

What controls the movement of substances in and out of the nucleus?

The nuclear pores on the double membrane of the nucleus

Mitochondria supply energy to the cell in a process know as…

Mitochondria supply energy to the cell in a process know as __respiration__

Why would some cells need to contain more mitochondria?

Some cells require lots of energy ex. muscle cells

The … of the mitochondria produce energy

The __inner foldings__ of the mitochondria produce energy

The more … a mitochondrion has the more energy it is producing

The more __folds__ a mitochondrion has the more energy it is producing

Draw a diagram of an active mitochondrion and an inactive mitochondrion. State the difference

* The active mitochondrion has __more folds__ since it produces __more energy__ in comparison to the inactive mitochondrion

What energy carrier is a source of energy for cells?

ATP

Within a chloroplast, where is chlorophyll contained?

Chlorophyll is contained in __thylakoids__, in stacks of thylakoids called grana.

What is the difference between grana and thylakoids?

* Thylakoids are membrane bound compartments or disks where the light reaction takes place. 
* Grana are the stacks of these thylakoid disks formed inside the chloroplast.

This is the key difference between grana and thylakoids

Where is the suns energy trapped, and where do light reactions occur?

In the chloroplast - grana - thylakoids

What is the cell wall composed of?

protein , cellulose, polysaccharides

Name 3 differences between an animal and a plant cell

__Plant Cell:__

* Cell wall (shape is rigid)
* Large vacuoles
* Chloroplasts

\
__Animal Cell__

* No cell wall (shape can change)
* Small vacuoles
* No chloroplasts

The structure of a cell seen with the electron microscope is known as the ….

The structure of a cell seen with the electron microscope is known as the __ultrastructure__

List 4 functions of the cell membrane

1. retains organelles in the cell
2. acts as a selectively-permeable barrier
3. contains receptor sites (for matching molecules such as hormones)
4. displays antigens (molecules that stimulate the formation of anitbodies

What is the cytosol?

liquid part of the cytoplasm

List 3 functions of the cytoplasm

1. separates organelles
2. acts as a storage area for food, salts
3. chemical reactions occur there

Chromosomes are only visible when they are…

Chromosomes are only visible when they are __dividing__

What are 3 functions of the nucleus?

1. controls cell structures and function
2. DNA replication and nuclear division
3. controls the formation of mRNA

What is the nuclear membrane?

a double lipo-protein membrane with pores.

* retains the nuclear contents
* has pores to allow materials in and out of the nucleus

What does RNA stand for?

Ribonucleic acid

What is a ribosome composed of?

proteins and RNA (ribonucleic acid)

What are 2 functions of the cell wall?

(i) to give strength and support to the cell and the whole plant

(ii)to prevent plant cells from bursting when water is taken in by osmosis (It allows the development of turgor.)

Give 3 functions of the vacuole

(i) stores water (this makes the cell turgid)

(ii) stores food (sugar, salt, protein, amino acids, etc.)

(iii) holds gases (02 , CO2)

Cells were discovered by …. in 1665

Cells were discovered by __Robert Hooke__ in 1665

When looking at animal cells under the microscope, describe how you obtained a sample of the cells

Rubbed the inside cheek with a swab

Why is a coverslip used?

• to protect the lens

• to protect the sample from drying out

Describe how you examined cells using the microscope

1. Focus using coarse focus

2. Focus using fine focus

   (Marking scheme 3+3)

State the precise location of the cell membrane in plant cells

immediately inside the cell wall

1. With what type of cell do you associate membrane-bound organelles?

2. What corresponding term is used to describe bacterial cells?

1. Eukaryotic

2. Prokaryotic

The cell membrane is described as being selectively permeable, what does this mean?

Only some substances allowed through

Why is diffusion alternatively known as passive transport?

No (or little) energy (ATP) required

Osmosis is described as a ‘special case of diffusion’ Explain why.

The movement of water or (osmosis) requires a membrane

Name the structure by which Amoeba gets rid of excess water that has entered by osmosis

Contractile vacuole

Give two locations in a cell at which there is a selectively permeable membrane

• nucleus, vacuole or chloroplast, mitochondrion

Explain the biological basis for the use of high sugar or high salt concentrations in the preservation of food.

bacteria loses water by osmosis and this causes death

In the human diet zinc, iron and copper are examples of…

In the human diet zinc, iron and copper are examples of trace elements.

The walls of xylem vessels are reinforced with…

lignin

Where in the cell would you expect to find phospholipids?

cell membrane

Vitamin … is an example of a water soluble vitamin.

Vitamin C is an example of a water soluble vitamin.

Name a disorder associated with the deficiency of vitamin D

rickets

What are the final products of digestion of a protein?

amino acids