LIFE SCIENCE - Bryan High School

LIFE SCIENCE What You Need to Know Explain that cells are the basic units of structure and function of living organisms, that once life originated all cells come from pre-existing cells, and that there are a variety of cell types. Explain that living cells: a. are composed of a small number of key chemical elements (C, H, O, N, P, and S); b. are the basic unit of structure and function of all living things; c. come from pre-existing cells after life originated; and d. are different from viruses. Compare the structure, function, and interrelatedness of cell organelles in eukaryotic cells (e.g. nucleus,

chromosome, mitochondria, cell membrane, cell wall, chloroplast, cilia, flagella) and prokaryotic cells. Cell Theory Cells come only from other cells. The old theory was called spontaneous generation and was disproved by Redi. Cell theory began with the invention of the microscope by van Leeuwenhoek in the 1600s.

Hooke called the building blocks of living things cells. There are two basic cell types: prokaryotes and eukaryotes that contain membrane-bound organelles. Viruses are not living and have only nucleic acids in a protein coat. They can only reproduce inside a living cell. Cell Organelles Only eukaryotic cells have these: a. nucleus directs all cell functions b. nucleolus makes ribosomes c. cell wall found only in plant cells, hold cell together d. ribosomes make proteins following DNA directions e. cytoplasm clear gel inside the cell

f. endoplasmic reticulum site of cellular chemical reactions h. Golgi apparatus sorts and holds proteins until needed i. vacuoles temporary storage of materials j. lysosomes contain digestive enzymes k. mitochondria transform energy for the cell l. chloroplasts capture light energy and convert to chemical m. centrioles help with cell division n. cilia and/or flagella help cell move, if there at all Pictures of Cell Types All cells fall into one of the two major classifications of prokaryotes and eukaryotes. Prokaryotes were here first and for billions of years were the only form of life. Eukaryotes are more organized and appeared later. There are some of both on Earth today. Explain the characteristics of life as indicated by

cellular processes and describe the process of cell division and development. Explain the characteristics of life as indicated by cellular processes including: a. homeostasis; b. energy transfers and transformations; c. transportation of molecules; d. disposal of wastes; and e. synthesis of new molecules. Summarize the general processes of cell division and differentiation, and explain why specialized cells are useful to organisms and explain that complex multicellular organisms are formed as highly organized arrangements of differentiated cells. Cellular Processes

There are many cellular processes. We will focus on: a. homeostasis regulation of internal environment to help guarantee survival b. energy transfers and transformations making food from light, extracting energy from food (respiration, photosynthesis, fermentation, digestion) c. transportation of molecules supply cells with nutrients d. disposal of wastes removal from cells or organisms e. synthesis of new molecules proteins made in ribosomes, following instructions from DNA Cell Division

There are two types of cell division: a. Meiosis Meiosis is the process that shuffles the genes around. Plants do it, animals do it, and even fungi do it (sometimes). Instead of creating two new cells with equal numbers of chromosomes (like mitosis), the cell does a second division soon after the first. That second division divides the number of chromosomes in half. This is sexual reproduction. b. Mitosis - The big idea to remember is that mitosis is the simple duplication of a cell and all of its parts. It duplicates its DNA and the two new cells (daughter cells) have the same pieces and genetic code. Two identical copies come from one original. Start with one; get two that are the same. This is asexual reproduction. Both types of cell division are very important. Explain the genetic mechanisms and

molecular basis of inheritance. Illustrate the relationship of the structure and function of DNA to protein synthesis and the characteristics of an organism. Explain that a unit of hereditary information is called a gene and genes may occur in different forms called alleles (e.g., gene for pea plant height has two alleles, tall and short). Describe that spontaneous changes in DNA are

mutations which may or may not be passed on to future generations. Use the concepts of genetics to explain inheritance. Hereditary Information

Mendel was one of the first geneticists, working with pea plants. Chromosomes are made of genes and genes can be of different types, called alleles. Alleles determine traits. Genes can be dominant or recessive or neither. Some traits are determined by more than one gene. Some diseases are genetically determined, like cystic fibrosis, etc. Genotype is your genetic code; phenotype is the outward appearance of those genes or the trait itself. Homozygous is when an organism possesses 2 identical genes for a trait; heterozygous is one of each gene. (TT or Tt). Sex-linked traits, such as red-green color blindness and hemophilia, are carried on the sex chromosomes (X and Y in humans). Mutations

Mutations are changes in DNA sequence. They can be caused by errors in replication, transcription, cell division, or external agents (such as radiation, chemicals, and even high temperatures). Mutations are especially significant if passed from one generation to another. Mutations, by effecting the DNA sequence, can also affect the ability to make important proteins. It is difficult, or impossible, to repair damaged DNA.

Tracing Inherited Traits Punnett squares are often used. Pedigrees can also be used. Explain the flow of energy and the cycling of matter through biological and ecological systems (cellular, organismal, and ecological).

Describe how matter cycles and energy flows in living systems and between living systems. Describe how cells and organisms acquire and release energy. Explain that living organisms use matter and energy to synthesize a variety of organic molecules and to drive life processes. Energy and Food Webs As predators eat prey and consumers eat producers, energy is transferred from one

organism to another. What happens when the chain is disrupted? For instance, all the snakes are killed by a disease. How does this affect the other living things? Explain how evolutionary relationships contribute to an understanding of the unity and diversity of life.

Describe that biological classification represents how organisms are related with species being the most fundamental unit. Explain that variation of organisms within a species increases the likelihood that at least some members of a species will survive under changing conditions. Relate diversity and adaptation to structures and their functions in living organisms. Classification

There are 6 Kingdoms: Eubacteria, Archaebacteria, Protists, Fungi, Plants, and Animals. Each Kingdom is then broken down into phylum, class, order, family, genus, and species. Animals in a species are the MOST related to each other. Scientific names use the genus and species names (Genus species). Canis rufus is a red wolf, Canis latrans is a coyote, and Canis lupus is a grey wolf. They are different species because of physical traits. Usually one species cannot breed with other species and produce fertile offspring. Survival of the Fittest

Genetic changes can be caused by mutation, genetic drift, and gene flow. Some genes protect organisms from one thing but endanger them in other ways. Presence of sickle cell anemia gene protects people from malaria. Where the person lives may determine which is better. Explain the structure and function of ecosystems and relate how ecosystems change over time.

Explain how living things interact with biotic and abiotic components of the environment. Relate how distribution and abundance of organisms and populations in ecosystems are limited by the ability of the ecosystem to recycle materials and the availability of matter, space and energy. Conclude that ecosystems tend to have cyclic fluctuations around a state of equilibrium that can change when climate changes, when new species appear as a result of immigration or when species disappear. Ecosystems

Ecosystems vary in size. They can be as small as a puddle or as large as the Earth itself. Any group of living and nonliving things interacting with each other can be considered as an ecosystem. Within each ecosystem, there are habitats which may also vary in size. A habitat is the place where a population lives. A population is a group of living organisms of the same kind living in the same place at the same time. All of the populations interact and form a community. The community of living things interacts with the non-living world around it to form the ecosystem. The habitat must supply the needs of organisms, such as food, water, temperature, oxygen, and

minerals. If the population's needs are not met, it will move to a better habitat. The processes of competition, predation, cooperation, and symbiosis occur. Biomes are ecosystems where several habitats intersect. Describe how human activities can impact the status of natural systems. Describe ways that human activities can deliberately or inadvertently alter the equilibrium in ecosystems. Explain how changes in technology and biotechnology can cause these same kinds of changes. Illustrate how uses of resources at local, state, regional, national, and global levels have

affected the quality of life. Describe a foundation of biological evolution as the change in gene frequency of a population over time. Explain current and historical developments. Describe how scientists continue to investigate and analyze aspects of evolutionary theory. Recognize that a change in gene frequency is a foundation for evolution. Explain about natural selection.

Describe some historical developments that occurred in evolutionary thought. Describe how scientists continue to investigate and analyze aspects of evolutionary theory. Evolutionary Thoughts Things change. The process of cars changing over the past 100 years can be thought of as an evolution in engineering. When an organism changes over many

generations, it might be better suited to live, or more likely to die. If the change was that you are a 500-pound bird with little tiny wings and little tiny legs, chances are you wouldn't move around too well. One day you might run out of food and die or be eaten. Mutations, genetic drift, and migration may help this process of evolution. Fossil evidence shows changes in organisms over time. Convergent Evolution CONVERGENT EVOLUTION This is when two totally different species develop similar traits. Outside natural factors create a situation

where that skill is a benefit. For example, you are a plant and I am an animal. We both have animals hunting us and eating us. We need protection. So we both develop spines to poke the hunters. The spines are made in different ways but do the same job. You are a cactus and I am a porcupine. Divergent Evolution DIVERGENT EVOLUTION We start as the same species, but then as more generations develop, my group becomes good at one thing and yours at another. Bird beaks are a good example for this one. One species of bird can develop in different directions depending on what type of food it eats. Their beaks develop different shapes after

many generations. Charles Darwin used bird development in many of his scientific papers. Explain how natural selection and other evolutionary mechanisms account for the unity and diversity of past and present life forms. Analyze how evolutionary mechanisms provide a scientific explanation for the diversity and unity of past and present life forms. Explain that life on Earth is thought to have begun about 4 billion years ago. During most of the history of Earth, only single celled organisms existed but once cells with nuclei developed, increasingly

complex organisms evolved. Summarize the historical development of scientific theories and ideas, and describe emerging issues in the study of life sciences. Use historical examples to explain how new ideas are limited by the context in which they are conceived. Describe advances in life sciences that have important long-lasting effects on science and society.

Analyze and investigate emerging scientific issues, such as genetically modified food, stem cell research, and cloning. Biotechnology Some examples of biotechnology are: a. imaging (X-rays, scans, etc) b. genetic engineering c. genome projects d. newer and better microscopes e. stem cell research f. cloning g. genetically modified foods.

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