Cell Processes and Energy Chapter 2 Cell Processes and Energy

Section 4 Photosynthesis

Producers and Consumers Autotroph = Producers Heterotrophs = Consumers

Process of Photosynthesis Process by which organism captures energy from the sun and uses it to make food Stage 1: Capture sun’s energy Green pigment called chlorophyll captures light energy from sun Stage 2: Making food

Making food for plants Raw materials (needs) Products Water – taken in by the roots Carbon dioxide - enters the stomata (small opening on the underside of the leaves) Products Oxygen – most of it leaves the plant through the stomata Sugar – glucose – C6H12O6 – food for plant

Photosynthesis Equation Carbon dioxide Water Glucose Oxygen

Photosynthesis and Life Nearly all living things either directly or indirectly receives energy from sun EX: plant (autotroph- energy from sun) Herbivores – eat plants and receive the sun’s energy from the plant Carnivores – eat herbivores and receive the sun’s energy from their food

Respiration

Storing and releasing energy When you eat, energy from the food is stored. When you need energy, food is broken down to release energy. Respiration: process of breaking down food to release energy Cells need a continuous supply of energy so respiration is always occurring.

Respiration Equation Glucose Oxygen Carbon dioxide Water Carbon dioxide and Glucose comes from the food water diffuse out of cell Oxygen comes from the air or water

2 stages of respiration Stage 1 – cytoplasm Stage 2 – mitochondria Glucose is broken down No oxygen is needed Only a small amount of energy is released Stage 2 – mitochondria Glucose further broken down Oxygen is needed Energy released

Photosynthesis and Respiration Opposite processes The 2 together form a cycle keeping oxygen and carbon dioxide in the atmosphere

Fermentation Provides energy for cells without oxygen Less energy than respiration 1. Alcohol fermentation Yeast – produces carbon dioxide (bread rises) 2. Lactic acid fermentation Occurs when you exercise Your cells need oxygen faster than you can take it in Fermentation occurs to produce energy and a product is lactic acid. This causes your muscles to ache.

Cell division

Functions of cell division Growth Repair (broken bone, cut) Reproduction (single celled organisms)

The Cell cycle Regular sequence of growth and division A parent cell divides to form 2 identical daughter cells 3 main stages Interphase Mitosis Cytokinesis

Stage 1: Interphase A. Growth B. DNA replication Doubles in size Copies all organelles B. DNA replication Copy DNA C. Preparation for division Produces structures necessary for division

Stage 2: Mitosis Cell’s nucleus divides into 2 nuclei 4 phases Prophase: Nucleus condenses to form chromosomes Metaphase: Chromosomes line up in the middle of the spindle Anaphase: Chromatids move to end of cell Telophase: new nuclear membrane forms

Stage 3: Cytokinesis Cytoplasm divides Organelles divide Animal cell: cell membrane squeezes together to form 2 cells Plant cell: Cell plate forms between the cells. This becomes a cell membrane. The cell wall forms outside it

Length of cell cycle Different for each cell Urchins 2 hours Liver cells 22 hours Brain cells Never Prep for Division 2 hours Cell Division 1 hour DNA Replication 10 hours Growth 9 hours