Characteristics of life and Cellular Respiration

Characteristics of Living Things There are 8 characteristics that all living things share:

Characteristics of Living Things All living things are made up of cells - living matter enclosed by a barrier that separates it from its surroundings. There are two basic kinds of organisms – a. unicellular (single-celled) b. multicellular (many celled) c. prokaryote (no nucleus) d. Eukaryote (nucleus) There are 8 characteristics that all living things share. First of all, all living things are made up of cells. A cell is living matter enclosed by a barrier, or membrane, that separates it from its surroundings. There are 2 basic kinds of organisms: unicellular or single celled and multicellular or many celled. The unicellular organisms have to carry on all life processes within that single cell. Multicellular organisms have cells and tissues that are differentiated to perform different jobs. Unit 2 Notes

Characteristics of Living Things 2. All living things reproduce - produce new organisms through a process called reproduction. There are two kinds of reproduction: sexual (two parents unite – sharing their genes to produce the 1st cell of the offspring) meiosis b. asexual (single parent – single cell divides or portion of organism splits off to form a new one) mitosis, regeneration, budding, binary fission Second, all living things reproduce or produce new organisms through a process we call reproduction. There are 2 kinds of reproduction: sexual reproduction, where 2 parents unite to share their genes and produce the first cell of the offspring, and asexual reproduction, where there is a single parent organism. If the organism is unicellular, then the single cell divides to produce 2 cells. If the organism is multicellular, then a portion of the organism splits off to form a new one – like rooting a cutting of a plant.

Characteristics of Living Things 3. All living things are based on a universal genetic code. a. The genetic code is called DNA b. This means offspring inherit traits from their parents through genes carried on DNA. Third, all living things are based on a universal genetic code. The genetic code is found in the DNA, or deoxyribonucleic acid, that makes up chromosomes and genes. This means the offspring inherit traits from their parents through the genes carried on the DNA.

Characteristics of Living Things 4. All living things grow and develop. Unicellular organisms grow in size only; multicellular growth includes development and differentiation of organs and tissues. (This means different cells, tissues, and organs do different jobs but all have the same DNA.) The fourth characteristic that all living things share is that all of them grow and develop. Unicellular organisms grow in size only – once they reach a certain size they divide to produce 2 daughter cells, each of which then grow. Multicellular organisms also grow in size, but their growth also includes development and differentiation of organs and tissues. This means different cells, tissues, and organs do different jobs.

Characteristics of Living Things 5. All living things obtain and use materials and energy. A. This is called metabolism - Autotrophs (producers) - organisms which obtain energy directly from the sun & store it through photosynthesis Heterotrophs (consumers) - organisms which obtain energy by eating other organisms Number 5, all living things obtain and use materials and energy. This is called metabolism – the combination of all the chemical reactions through which the organism builds up or breaks down the materials it needs to sustain life. These include digestion, respiration, photosynthesis, etc. There are 3 metabolic categories all organisms can belong to:

Cellular Respiration B. All things get energy from Cellular Respiration - Conversion of food energy (glucose) into cell energy (ATP) Autotrophs are organisms which obtain energy directly from the sun and store it through a process called photosynthesis. Auto means self and troph refers to feeding, so autotrophs are self-feeders. Plants are autotrophs. Heterotrophs are organisms which obtain energy by eating other organisms, either autotrophs or heterotrophs. We are heterotrophs. The third category is the decomposers. These are organisms like bacteria and fungi that obtain their enery from the remains of dead organisms. Even if it sounds disgusting, we’re lucky to have decomposers – think how gross it would be if dead stuff never decayed!

What do you notice about this equation? Chemical Equation C6H12O6 + 6O2  6CO2 + 6H2O + Energy Glucose + Oxygen  Carbon + Water + Sunlight (sugar) Dioxide What do you notice about this equation?

Steps of Cellular Respiration 1. Glycolysis Takes place in cytoplasm Does NOT require O2 Converts : Glucose  2 molecules pyruvic acid + 2 ATP molecules

Steps of Cellular Respiration Cont’d Krebs Cycle Takes place in mitochondria REQUIRES O2 Breaks down: Pyruvic acid Acetyl-CoA + CO2 + 2 ATP (energy)

Krebs Cycle Krebs Cycle

Steps of Cellular Respiration Cont’d 3. Electron Transport Chain a. Occurs in the mitochondria b. Process where NADH and FADH2 are changed into ATP NADH + FADH2 + O2  H2O + 32 ATP

Steps of Cellular Respiration A net total of 36 ATP are made Electrons carried in NADH Pyruvic acid Electrons carried in NADH and FADH2 Glucose Krebs Cycle Electron Transport Chain Glycolysis cytoplasm 2 2 32

2 Types of Cellular Respiration 1. Aerobic – needs oxygen to continue O2 must be present 36 ATP can be made from 1 glucose molecule Ocurrs in 3 stages 2. Anaerobic – doesn’t need oxygen to continue Occurs when no oxygen is present 2 ATP can be made from 1 glucose molecule during stage one of glycolysis

If no oxygen is present . . . 1. Alcoholic Fermentation Does NOT occur in animal cells It occurs in yeast and a few other microorganisms Converts:   Glucose  ethyl alcohol, CO2, & ATP (small amount) 2. Lactic Acid Fermentation Occurs in some animal cells Produces enough energy for glycolysis to continue Buildup in muscles leads to muscle soreness

Characteristics of Living Things 6. All living things respond to their environment by detecting and responding to stimuli - signals to which they respond. phototropism, gravitropism, etc The sixth characteristic of living things is that all living things respond to their environment by detecting and responding to stimuli. A stimulus is a signal to which something responds. For instance, plants grow toward their source of light – that’s definitely a response. What about temperature? If it’s cold, we put on a sweater, or lizards find a sunny spot to lie int. Those are also responses. You can probably think of a lot of other stimuli that organisms respond to.

Characteristics of Living Things 7. All living things must maintain a stable internal environment. This process is called homeostasis and involves the use of feedback mechanisms (like a thermostat). Seventh, all living things must maintain a stable internal environment. This is called homeostasis and is a very important concept in biology. Homeostasis involves the use of feedback mechanisms. A good example of a feedback mechanism is a thermostat. When it’s cold outside and the temperature inside dips below the thermostat setting, what happens? The heater comes on, of course. When the room heats up to the temperature the thermostat is set on, the heater turns off. This is called feedback – the thermometer in the thermostat reads the room temperature and turns a switch on or off as needed to maintain the temperature setting. That’s very much like maintaining homeostasis. Unit 2 Notes

Characteristics of Living Things 8. As a group, living things change over time or evolve, which allows for survival in an ever-changing world. As environments change, organisms become better or less able to survive based on their characteristics. Finally, as a group, living things change over time or evolve, which allows for survival in an ever-changing world. As environments change, organisms become better or less able to survive based on their characteristics. The important thing to remember here is that different organisms are suited to exist in different environments. If the environment changes and you can’t adapt, your species may well become extinct! Unit 2 Notes