DNA, Chromosomes, and Genes

DNA The scientific name for DNA is deoxyribonucleic acid. Found in the nucleus of eukaryotic cells, found in the cytoplasm of prokaryotic cells.

Purpose of DNA The job of DNA is to be the “how to” manual for the cell. It tells the cell when/how it should grow, develop, repair, reproduce and more. DNA is also often referred to as a “blueprint” of a living thing. One cell in your body contains all the genetic information to make all the other cells that make you. Think of the DNA as being volumes of encyclopedias on how to build you.

DNA, What does it look like?

http://www.ncbi.nlm.nih.gov/

DNA, What does it look like? When the DNA is being used (read) it has to be rolled out. It looks like yarn or spaghetti inside the nucleus. You have 46 strands of DNA in your body that are paired up. So there are 23 pairs of DNA strands.

Genes A gene is the functional and physical unit of heredity passed from parent to offspring. Are a small piece of a DNA strand that determines a specific characteristic or trait. It usually makes a specific protein.

What does a Gene Look Like?

http://www.ncbi.nlm.nih.gov

Chromosomes DNA isn’t always rolled out, when it needs to be moved it becomes “Packaged”. A DNA wraps itself around proteins forming a neat, easy to move, package. These packages are known as chromosomes. Each species has a specific number of chromosomes (packages/volumes). Ex: Cat 38 Buffalo 60 Dog 78 Human 23

What do chromosomes look like?

http://www.ncbi.nlm.nih.gov

Genome A genome is all the DNA contained in an organism or a cell, which includes the chromosomes plus the DNA in mitochondria (and DNA in the chloroplasts of plant cells).

What does a Genome Look Like?

http://www.ncbi.nlm.nih.gov

Where do we get DNA FROM? It depends…

Methods of Reproduction

Types of Reproduction There are two main ways in which reproduction occurs: Asexual Reproduction Sexual Reproduction

Asexual Reproduction: requires only 1 parent and the offspring are an exact copy of the parent---a clone

Asexual Reproduction: Organisms that reproduce asexually cannot develop much variety, because they are “copying” the original organism exactly.

Methods of asexual reproduction: Binary fission Budding Fragmentation

Binary fission This is called binary fission. Single-celled organisms (Amoeba, paramecium, euglena) which use asexual reproduction can do so simply by dividing into two equal halves. This is called binary fission.

When conditions are good, such as plenty of water, food, right temperatures, etc., binary fission is a very effective way of producing many, many offspring. For example, the cell of a Paramecium can divide, grow, and divide again in the space of 8 hours.

Budding- an offspring grows out of the body of the parent. Hydra Budding offspring Cactus Budding

Budding Yeast - budding In yeasts the cell does not divide equally in two halves; instead, there is a large mother cell and a smaller daughter cell. Yeast - budding

Fragmentation In this form, the body of the parent breaks into distinct pieces, each of which can produce an offspring. Pieces of coral broken off in storms can grow into new colonies. A new starfish can grow from one detached arm.

Fragmentation- plant cuttings Some plants can grow from cutting them up and replanting them.

Green plants are quite sophisticated in their methods of asexual reproduction. Offspring may be produced by runners, bulbs, rhizomes or tubers.

What is sexual reproduction? Requiring 2 parents male and female Offspring are different from the parent organism because it takes half the DNA from one parent and half from the other

Sexual Reproduction Sexual reproduction produces a greater chance of variation within a species than asexual reproduction would. This variation improves the chances that a species will adapt to his environment and survive.

Sexual vs. Asexual Reproduction Asexual reproduction results in offspring that are genetically identical to the parent organism. Sexual reproduction results in offspring that are genetically different from the parent organisms.

https://www.youtube.com/watch?v=zwibgNGe4aY https://www.youtube.com/watch?v=5MQdXjRPHmQ

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