Cells – the basis of life! Key learnings
This week we investigated the parts of cells and what they do, and how material is transported across the cell membrane.
Cellular components are called cell organelles. Different organelles have important functions in the life and processes of the cell.
Some organelles work by giving shape and backing, while some help with the movement and generation of cells.
Among the organelles we looked at were the:
| Cytoplasm | The jelly-like material that makes up much of a cell inside the cell membrane, and, in eukaryotic cells, surrounds the nucleus. |
| Golgi apparatus | A stack of small flat sacs formed by membranes inside the cell’s gel-like fluid (cytoplasm). The golgi apparatus prepares proteins and fat (lipid) molecules for use in other places inside and outside the cell. |
| Lysosomes | Lysosomes are small membrane-bound organelles. The main function of these is digestion. |
| Mitochondria | The mitochondria are oblong-shaped organelles that are found in the cytoplasm of every plant and animal cell. They are the main power generators, converting oxygen and glucose into energy. |
| Nucleolus | The nucleolus is the control centre of the cell. An area inside the nucleus of a cell that is made up of RNA and proteins and is where ribosomes are made. Ribosomes help link amino acids together to form proteins. |
| Vacuoles | Site of fluid and nutrient storage provides plant cells with support. Large in plant cells. |
| Ribosomes | Ribosomes take information (mRNA) converted from the DNA in the nucleus and manufacture proteins for the body to use. |
| Endoplasmic reticulum (ER) | The ER is a folded membrane continuous with the nuclear membrane. The rough ER has membrane-bound ribosomes for producing proteins. The smooth ER lacks ribosomes and is involved in membrane production, the synthesis of lipids and steroids, and the storage of calcium for muscle contractions. |
We also learnt that nutrients required by the cell need to cross the cell membrane. Cellular waste must be removed across the cell membrane and some substances must be moved around the cell. Transportation can be either by active or passive means.
Passive transport across the cell membrane requires no additional energy (ie like a ball rolling down a hill). Passive transport can be via:
- Diffusion
- Facilitated diffusion
- Osmosis
Active transport is the transport of molecules that require the use of energy, in the form of an energy-storing chemical called ATP (adenosine triphosphate) to help them cross the cell membrane (ie pushing a ball up a hill). Active transport can be via:
- Ion pumps – a special protein that moves ions (charged molecules) across the membrane
- Exocytosis – the active removal of substances from the cell
- Endocytosis – a cell actively takes something in.
Hope you enjoyed touring the inside of a cell this week and figuring out more about what the parts do!
Let’s now remind you of what we covered in Week 1, and then you might like to pick your top two new learnings from this course and share them in a discussion.
Last week, we learnt an acronym to help remember the 7 things living organisms have to do to survive:
The features of living organisms were:
- Movement
- Respiration
- Sensitivity
- Growth
- Reproduction
- Excretion
- Nutrition
We explored unicellular and multicellular organisms – prokaryotes and eukaryotes. Plants and animals have eukaryotic cells.
We looked at the hierarchical structure inside multicellular organisms. Cells were at the bottom, followed by tissue, organs, organ systems and the organism.
We investigated some features of plant and animal cells. Plant growth can be defined as an irreversible increase in size or volume. In plants, growth is brought about by a combination of cell division and cell enlargement. Animal cells come in various shapes and sizes, are mostly round, and grow by increasing cell numbers.
Note down at least two things that most interested you during your learning. See you back for a discussion of these next!
Andrea
The Basis of Life: Understanding Human Cells
The Basis of Life: Understanding Human Cells
Reach your personal and professional goals
Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.
Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.
