Characteristics of Life

Biology 101

Lisa Tuckey

Unit 1

Biology – the study of life.

Photo Starr Evers and Starr,8e, Fig. 1.4a, p. 6

What is Life?

• What does it mean to be alive?

• What differentiates you from a rock?

• Before continuing to the next slide, please pause the presentation and jot down what you think it means to be alive.

• What characteristics make you alive?

• When you have written down everything you can think of, please continue.

Different Life Forms

• The following photos are courtesy of Starr Evers and Starr, 2011

• What are the following life forms?

Fig. 1.6a1, p. 8

Fig. 1.6a2, p. 8

Fig. 1.6a3, p. 8

Fig. 1.6a4, p. 8

Fig. 1.6a5, p. 8

Fig. 1.6a6, p. 8

Fig. 1.6b1, p. 8

Fig. 1.6b2, p. 8

Fig. 1.6c1, p. 9

Fig. 1.6c2, p. 9

Fig. 1.6c3, p. 9

Fig. 1.6c4, p. 9

Fig. 1.6c5, p. 9

Characteristics of Life

• 1. Ability to sense and respond

• 2. Metabolism – aquire and use energy in chemical reactions (covered in the next few units)

• 3. Ability to grow and reproduce

• 4. Contain genetic Material – i.e. DNA

• 5. Consist of at least one cell.

Sense and Respond

• The ability to sense and respond to internal and external stimuli

– means that an organism can sense the world around them –

• E.g. ambient temperature or sound waves,

• Can constantly monitor their internal environment.

Metabolism

• All activities within a body occur because of chemical reactions.

• The term metabolism refers to ALL of the reactions that occur within an organism, not just the ones pertaining to what we eat, which is a common misconception.

Growth and Reproduction

• All organisms have the ability to repair cells and produce replacement cells.

• All organisms also have the ability to create another version of itself, to reproduce, either by itself or with another of its kind.

Genetic Material

• All organisms contains genetic material –which is passed onto their offspring during reproduction.

• That genetic material (DNA) is actually telling the cells of the body what to do.

• All of the reactions referred to earlier are determined by the DNA in each cell.

Thanks to Ramberg Media Images for DNA flickr image

This photo has Some Rights Reserved

Cellular• All life forms consist of at least one cell.

• Unicellular organisms – consist of one cell only e.g. bacteria.

• Multicellular organisms – consist of more than one cell.

• A cell is a self-contained unit of life – it actually exhibits all of the characteristics we have mentioned above. –senses and responds, metabolizes, contains DNA, grows and reproduces.

• In the following units we will be returning to each of these characteristics in much more detail.