Hi and Welcome to this episode of the “So you are studying for your exam” video review. One of many in the Sci Kap video series. This first episode deals with “Things You Really Should Remember and Understand from Semester 1” As with all the episodes in this series, the standard disclaimer applies… This is a REVIEW and only a review of key points and Learning Target concepts of the unit and is based on the premise of prior learning of the unit. It is not meant as a stand-alone teaching lesson. So let’s get started.

Since this is a review for the biology final it is important that you remember that Biology is the study of life. Basically, learning about living organisms and their interactions with other living and nonliving things. In order to be classified as a living organism, something must meet every criteria of the following comprehensive list: Be composed of cells. Cells are the basic unit of life. An organism can be single-celled or multicellular. The organism must possess a system of bio-organization where all parts interact to form the whole.

3. An organism must require and use energy by carrying on metabolism which is all the chemical reactions within the organism. Organisms need to respond to stimuli both to the internal and external environment and maintain homeostasis. Organisms need to display heredity through their DNA and RNA. This means organisms grow and develop using the DNA as instructions and the RNA to synthesize the necessary proteins. Also, organisms pass their genetic instructions to their offspring. This means the species population can evolve and adapt.

In studying living things and their interactions there is a organized system of levels. Organism – any individual living thing. Population – a group of organisms of the same species living in the same geographical area. A species is a group of genetically similar enough organisms that they can interbreed and produce viable fertile offspring. Community – a group of many populations living in the same area. Ecosystem – all the living (biotic) and non living (abiotic) things interacting in the same area. Biome - major regional or global community of organisms characterized by climate conditions and plant life. Biosphere – Is the Earth and all the living things on it and all the places they inhabit.

The cell is the basic unit of life. All cells must have a cell membrane and cytoplasm just like a water balloon must have water and a balloon. As the basic unit of life, a cell must meet all the criteria of a living organism including maintaining homeostasis. In order to do this the cell must regulate and control what goes in and out of the cell. The cell membrane is selectively permeable meaning only certain substances can pass through while other substances cannot. Factors that affect permeability include; the size of the substance, charge of the substance and concentration gradient.

Cells can be classified into two broad categories. Prokaryotic cells are simple more primitive cells. The lack a nucleus and membrane-bound organelles. Bacteria are examples of prokaryotic cells. Eukaryotic cells are more complex. They have a nucleus that protects the DNA and have membrane-bound organelles such as mitochondria in animal cells and both mitochondria and chloroplasts in plant cells. You are made of eukaryotic cells and admit it, you are pretty complex!

Deoxyribonucleic acid or DNA is the instructions for all life and it is universal among the life forms on Earth. DNA is a double helix polymer similar in shape to a spiral staircase. The basic unit or monomer of DNA is a nucleotide. Each nucleotide is composed of three parts; 5-Carbon sugar (deoxyribose) Phosphate group One of four nitrogen containing bases. The three components are covalently bonded. The sugar and the phosphate components for the backbone rails of the molecule.

Since all four of the nucleotides contain the same sugar and phosphate components, they are named for base they contain. Adenine, Thymine, Guanine, and Cytosine. Due to hydrogen bonding sites the bases always pair up A-T and G-C. It is the hydrogen bonds between the bases that form the double stranded nature of DNA. The hydrogen bonds also allow for the two strands to separate for DNA replication and mRNA transcription.

From DNA we can access all the genetic instructions for life and life processes. This leads us to the Central Dogma of Biology. The Central Dogma states that information flows in one direction within a cell from DNA to RNA to Protein. DNA can replicate itself, DNA can be transcribed to make mRNA, mRNA carries genetic instructions to the rRNA, ribosomes read the mRNA code and tRNA brings the amino acids that the ribosome bonds together to make protein. It is this process that gives rise to the structures and enzymes necessary for life.

Thank you for watching this Final Exam video review on “Things You Really Should Remember and Understand from Semester 1” Look for more episodes in the “So You Are Studying for Your Exam” Sci Kap video series. As always, this Sci Kap Production science video was created using the awesomeness of Powtoons and music from freemusicarchive.org. Till next time, KThxBai.