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Course: Middle school biology - NGSS > Unit 1
Lesson 1: Cells and organismsCells and organisms
Review your understanding of cells and organisms in this free article aligned to NGSS standards.
Key points:
- Living things are called organisms. All organisms are made up of cells.
- Cells are the smallest unit that can carry out all of the functions of life. These functions include taking up nutrients and water, getting rid of waste, getting and using energy, and interacting with the environment.
- Unicellular organisms are made up of one cell. Multicellular organisms are made up of many cells. The cells in multicellular organisms are often specialized to carry out specific functions.
- All cells come from other cells. New cells are made through a process called cell division. During cell division, one cell grows and splits into two.
- Single cells are typically too small to be seen with the naked eye. So, people often view cells through a microscope.
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So I have 2 questions. 1 is last year we learned that atoms are the smallest things but this year we learned that cells are the smallest things so which is it. And number 2 if you have 2 unicellular things and they combine would that make it a multicellular(76 votes)
The cell is the smallest unit of life, and the atom is the smallest unit of a chemical element. Cells are much bigger, and they’re made up of many, many atoms.
Atoms aren’t even the smallest thing, though! They are made of tiny particles including protons, neutrons, and electrons. Protons and neutrons are made of even smaller things called quarks!
Two individual cells can be together to make something multicellular. If you take any two random cells, though, they won’t necessarily make a multicellular organism.(182 votes)
so i learned that cells can sometimes split called "cell division" but what i wonder is why do they split, and how do they split?(45 votes)
There are two types of cell division: mitosis and meiosis. Most of the time, when someone refers to “cell division,” they mean mitosis, the process of making new body cells. [[Meiosis is the type of cell division that creates egg and sperm cells.]]
Cell division happens when a parent cell divides into two or more cells called daughter cells. But your question is why and how. So, let me answer your questions.
**Why do cells split?**
Cells divide, or split, for multicellular organisms to grow and renew themselves. It is also important for cells to divide so that old or damaged cells can be replaced.
**How do cells split?**
During mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells. Cell division usually occurs as part of a larger cell cycle. This process is carefully done by your genes, because if done incorrectly, health problems can result.
Hope this helps!(66 votes)
Are all bacterias unicellular or just some?(67 votes)
Most bacteria are unicellular. Some species of bacteria build up colonies in which many individual cells unite. Cells within those colonies can share tasks and even adopt different morphology (the way they look). In several cases it is very difficult to decide whether something is a colony of many cells, or one big multicellular organism. Scientists have been debating about this for long time now.
Learn more about it here:
https://www.jstor.org/stable/24989125
https://onlinelibrary.wiley.com/doi/epdf/10.1002/bies.20740
https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1758-2229.2010.00215.x?casa_token=xG3l6_YtRx8AAAAA%3AV-6My7f896SeXRpQyshvIepvNNsJDnfpaEXcnFADjSpbqJ0B2nikZu-VvfKLXbD131QCjlI_ekm8UU8
https://royalsocietypublishing.org/doi/full/10.1098/rsif.2011.0102(71 votes)
- How long do cells live? And if they do not live very long how are we alive? And if it is because they multiply, how do we die?(31 votes)
Cells in your body are constantly dying, but also constantly reproducing, so you live a much longer life than your cells. We die not when our cells die, but when they stop preforming the functions they are supposed to.(55 votes)
is a cell smaller than a atom or Atoms the smallest thing ever(12 votes)- Cells are made up of many, many, many atoms, so they are definitely bigger than atoms.
Atoms are very small (brooklyn.cuny.edu says “ a row of 10^8 (or 100,000,000) atoms would stretch a centimeter, about the size of your fingernail. ”). However, there are things even smaller than atoms! Atoms are actually made up of some combination of protons, neutrons, and electrons. The protons and neutrons make up the nucleus at the center. Just for scale, if the whole atom were the size of an American football stadium, the nucleus would be the size of a golf ball inside of it!
I hope this helps!(35 votes)
what are cell divisions(10 votes)
Cell divisions may sound like different groups, but it is a process of a cell splitting into two to make more cells(22 votes)
- If we got cells and our parents got cells and our grandparents got cells and our ancestors got cells where did the first cell come from?(12 votes)
- To add on, here is a passage from the University of Washington: "First cells on ancient Earth may have emerged because building blocks of proteins stabilized membranes. Life on Earth arose about 4 billion years ago when the first cells formed within a primordial soup of complex, carbon-rich chemical compounds..."
Hope this helped.(3 votes)
- How many cells are there in a human body?(7 votes)
The average human has about 37.2 trillion cells!(19 votes)
- are there cells in human skin?(6 votes)
Yes. Each inch of your skin has approximately 19 million skin cells.(16 votes)
- What is that red blood cell(9 votes)
- this is a cell, which has protein called hemoglobin, that transports oxygen the lungs to the rest of the body.
imagine this, the hemoglobin is a car that transports the oxygen to and from somewhere, just like a taxi. then it drops the the oxygen off to its destination for example different types of organs.(9 votes)
