Cells, Photosynthesis & Respiration.ppt

Lecture-5

Cells, Photosynthesis & Respiration

What is cell?• The cell is one of the most basic and smallest units of life. • In the body, there are brain cells, skin cells, liver cells, stomach

cells, and the list goes on. All of these cells have unique functions and features. And all have some recognizable similarities.

2Jan 11, 2015 Cell, Photosynthesis & Respiration

Below is a labeled diagram of an animal cell


• Plasma membrane: All cells have a 'skin', called the plasma membrane, protecting it from the outside environment. The cell membrane regulates the movement of water, nutrients and wastes into and out of the cell. All the working parts of the cell are inside of the cell membrane. They are:

• • Nucleus: Nucleus is present at the center of the cell. It contains

the cell's DNA (the genetic code that coordinates protein synthesis). The transcription phase of protein synthesis takes places in the cell nucleus.

Important Parts of a Cell


Ribosome: One important cellular organelle is the ribosome. It participates in protein synthesis. After transcription phase is complete, RNA leaves the nucleus and travels to the cell's ribosome, where translation occurs. Mitochondrion: Another important cellular organelle is the mitochondrion. Mitochondria are often referred to as the power plants of the cell because many of the reactions that produce energy take place in mitochondria. Lysosome: Lysosomes are organelles that contain enzymes that aid in the digestion of nutrient molecules and other materials.

5

Important Parts of a Cell…

Jan 11, 2015 Cell, Photosynthesis & Respiration

Animal Cell vs Plant Cell• While both plant and animal cells contain the structures

discussed above, there are some differences between them. Plant cells have some additional specialized structures.


• Many animals have skeletons to give their body structure and support. Plants do not have a skeleton for support. This is because of a unique cellular structure called the cell wall. The cell wall is a rigid structure outside of the cell membrane.

• In addition, plant cells contain chloroplast that allows plants to harvest energy from sunlight. Specialized pigments in the chloroplast (chlorophyll) absorb sunlight and use this energy to complete the chemical reaction:

• 6 CO2 + 6 H2O + energy (from sunlight) C6H12O6 + 6 O2

• Carbon dioxide + Water Glucose + Oxygen• • In this way, plant cells manufacture glucose and other

carbohydrates.


Some differences between animal and plant cellsOrganonelles Animal Cell Plant Cell

Shape Round (irregular shape) Rectangular (fixed shape)

Plasma membrane only cell membrane cell wall and a cell membrane

Cell wall Absent Present

Vacuole One or more small vacuoles (much smaller than plant cells).

One, large central vacuole taking up 90% of cell volume.

Plastids Absent Present

Lysosomes Lysosomes occur in cytoplasm.

Lysosomes usually not evident.

Chloroplast Animal cells don't have chloroplasts

Plant cells have chloroplasts because they make their own food


Energy and Cell

• All living organisms require energy to conduct the many functions necessary to sustain life.

• The source of this energy for cells is the chemical bonds of food molecules.

• Cells can be thought of as chemical factories that conduct a variety of chemical reactions.


Photosynthesis and Respiration The process of converting sunlight energy to chemical-bond energy by the chloroplasts as sugar molecules is photosynthesis. It is one of the major biochemical processes through which plants produce food molecules such as carbohydrates for themselves as well as for all the other organisms on earth. On the other hand respiration, a second major biochemical process made by mitochondria, during which cells release the chemical-bond energy from food and supply to the cells into usable forms.

C6H12O6 6O2 6CO2 6H2O 36ATPglucose oxygen carbon

dioxidewater energy

Aerobic cellular respiration

6 CO2 + 6 H2O + energy (from sunlight) C6H12O6 + 6 O2



Photosynthesis RespirationOccurs in the presence of light (and chlorophyll in plant cells).

Occurs at all times in cells.

Requires energy (light) to make sugar (glucose).

Releases energy from sugar.

Complex substances (sugar) are formed from simpler ones (carbon dioxide and water).

Complex substances (sugar) are broken down into simpler ones (carbon dioxide and water).

Carbon dioxide and water are the raw materials.

Carbon dioxide and water are the waste products.

Oxygen is given out. Oxygen is taken in.


Probable Questions:

1. What is cell? Name different important parts of a cell. 2. Draw the picture an animal cell and label different parts in it..3. What are the differences between plant cell and animal cell?4. Describe the functions of chloroplast, cell wall, ribosome, mitochondrion etc.5. Discuss the importance of photosynthesis and respiration.6. Write the difference between photosynthesis and respiration at a glance.


Documents

Cells, Photosynthesis & Respiration.ppt