Active and Passive Transport Active and passive transport are biological processes that move oxygen, water and nutrients into cells and remove waste products. Active transport requires chemical energy because it is the movement of biochemicals from areas of lower concentration to areas of higher concentration. On the other hand, passive trasport moves biochemicals from areas of high concentration to areas of low concentration; so it does not require energy. Process There are two types of active transport: primary and secondary. Example of primary active transport, where energy from hydrolysis of ATP is directly coupled to the movement of a specific substance across a membrane independent of any other species. There are four main types of passive transport: osmosis, diffusion, facilitated diffusion and filtration. Three different mechanisms for passive transport in bilayer membranes. Video explaining the differences Here's a good video explaining the process of active and passive transport: Examples References
GCSE Bitesize: Growth Asexual Reproduction vs Sexual Reproduction - Difference and Comparison | Diffen Moon Jellies has two main stages in its life cycle – polyp stage (asexual reproduction) & medusa stage (sexual reproduction) Types There are several different types of asexual reproduction. These include budding, where the offspring grows out of the body of the parent, and gemmules, where the parent releases a specialized mass of cells that will become a new individual. There are two types of sexual reproduction. Process Asexual reproduction is reproduction that occurs without any interaction between two different members of a species. Cell division in asexual and sexual reproduction Sexual reproduction is reproduction that requires a male and a female of the same species to contribute genetic material. Examples Asexual reproduction is used by many plants, e.g. spider plants, bacteria, hydra, yeast, and jellyfish. Sexual reproduction is used by most mammals, fish, reptiles, birds and insects. Advantages and Disadvantages References
Sex Cells Sex cells are also called gametes. The gametes are the sperm and the egg; the more scientific terms for these cells are the spermatozoa and ova, respectively. These cells are made only in gonads, and they are made by a type of cell division that doesn't occur anywhere else in the body-- meiosis. You have probably learned about meiosis in a previous class, but I will review it a little bit here... There are two types of cell division. Meiosis, on the other hand, is only used for making gametes! The second reason that we have to use meiosis is because we need our spermatozoa and ova to contain only half of the normal amount of genetic information. Meiosis begins with one cell, called a germ cell (because it specifically makes gametes). Our cells have two copies of every type of chromosome. Use the diagram to follow the description in the next paragraph. Before our germ cells undergo meiosis, they proceed through DNA replication, during which every chromosome is copied.
Plant Cell vs Animal Cell Plant and animal cells have several differences and similarities. For example, animal cells do not have a cell wall or chloroplasts but plant cells do. Animal cells are round and irregular in shape while plant cells have fixed, rectangular shapes. Plant and animal cells are both eukaryotic cells, so they have several features in common, such as the presence of a cell membrane, and cell organelles, like the nucleus, mitochondria and endoplasmic reticulum. Chloroplasts Plants are autotrophs; they produce energy from sunlight through the process of photosynthesis, for which they use cell organelles called chloroplasts. Shape Another difference between plant cells and animal cells is that animal cells are round whereas plant cells are rectangular. Cell Wall Plant cells have a rigid cell wall that surrounds the cell membrane. Vacuoles Shape and size of vacuoles Animal cells have one or more small vacuoles whereas plant cells have one large central vacuole that can take up to 90% of cell volume.
mDNA replication zoom Cell Function: Meiosis What are the big ideas here? There are two cell divisions. Mitosis has one division and meiosis has two divisions. You still have to remember PMATI, but now you do it twice. You also need to remember that four cells are created where there was originally one. That's four (4) cells with half of the amount of DNA needed by a cell. Meiosis happens when it's time to reproduce an organism. As we said, meiosis happens when it's time to reproduce. That second division divides the number of chromosomes in half. MEIOSIS I: This is basically like the PMATI of a regular mitosis. This crossing over is an exchange of genes. MEIOSIS II: In Prophase II the DNA that remains in the cell begins to condense and form short chromosomes. Telophase II shows the DNA completely pulled to the sides and the cell membrane begins to pinch. Or search the sites for a specific topic.
Mitosis Internet Lesson Name: ________________________________________ In this internet lesson, you will review the steps of mitosis and view video simulations of cell division. You will also view an onion root tip and calculate the percentage of cells at each of the stages of cell division . Mitosis Tutorial at On the left side of the screen is a navigation bar, click on the link to “MITOSIS” Read the text on this page and view the animation, you can slow down the video by clicking step by step through the phases. 1. Watch the video carefully. 2. -- How many are in each daughter cell at the end of mitosis? --The little green T shaped things on the cell are: ____________________________ -- What happens to the centrioles during mitosis? 3. Another Mitosis Animation Go to . Onion Root Tip Online Activity at Read the introduction, then click the “next” button. You Draw It!
Eukaryotic Cell vs Prokaryotic Cell The distinction between prokaryotes and eukaryotes is considered to be the most important distinction among groups of organisms. Eukaryotic cells contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not. Differences in cellular structure of prokaryotes and eukaryotes include the presence of mitochondria and chloroplasts, the cell wall, and the structure of chromosomal DNA. Prokaryotes were the only form of life on Earth for millions of years until more complicated eukaryotic cells came into being through the process of evolution. Definition of eukaryotes and prokaryotes Prokaryotes (pro-KAR-ee-ot-es) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. Eukaryotes (IPA: [juːˈkæɹɪɒt]) are organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. Differences Between Eukaryotic and Prokaryotic Cells References Share this comparison:
How Cells Obtain Energy from Food - Molecular Biology of the Cell - NCBI Bookshelf Cell Function: Mitosis Eventually cells need to duplicate. There are two main methods of replication, mitosis and meiosis. This tutorial will talk about 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. Beyond the idea that two identical cells are created, there are certain steps in the process. We suppose it would be good to know what happens during those phases. Metaphase: Now all of the pieces are aligning themselves for the big split. Anaphase: Here we go! Telophase: Now the division is finishing up. Interphase: This is the normal state of a cell.
What is a gene mutation and how do mutations occur? A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people. Mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes. Gene mutations can be classified in two major ways: Hereditary mutations are inherited from a parent and are present throughout a person’s life in virtually every cell in the body. Genetic changes that are described as de novo (new) mutations can be either hereditary or somatic. Somatic mutations that happen in a single cell early in embryonic development can lead to a situation called mosaicism. Most disease-causing gene mutations are uncommon in the general population. The Centre for Genetics Education provides a fact sheet discussing variations in the genetic . More basic information about genetic is available from GeneEd. Next: How can gene mutations affect health and development?
DNA vs RNA DNA, or deoxyribonucleic acid, is like a blueprint of biological guidelines that a living organism must follow to exist and remain functional. RNA, or ribonucleic acid, helps carry out this blueprint's guidelines. Of the two, RNA is more versatile than DNA, capable of performing numerous, diverse tasks in an organism, but DNA is more stable and holds more complex information for longer periods of time. Structure DNA and RNA are nucleic acids. Nucleic acids are long biological macromolecules that consist of smaller molecules called nucleotides. Structural differences between DNA and RNA. DNA is found in the nucleus of a cell (nuclear DNA) and in mitochondria (mitochondrial DNA). During transcription, RNA, a single-stranded, linear molecule, is formed. RNA folding in on itself into a hairpin loop. In both molecules, the nucleobases are attached to their sugar-phosphate backbone. In RNA, adenine and uracil (not thymine) link together, while cytosine still links to guanine. Function Recent News