A1 - The Cell Flashcards
What is Cell Division?
Cell division is the process in which a parent cell divides, giving rise to two or more daughter cells. It is an essential biological process in many organisms. It is the means used by multicellular organisms in order to grow, replenish (repair), and reproduce.
What is Chromatin?
Chromatin is a genetic material that is not visible until just before cell division - it shortens and thickens and becomes recognizable as chromosomes (23 pairs/46 chromosomes). It holds the coding.
“Chromatin is the material of which the chromosomes of organisms other than bacteria (i.e. eukaryotes) are composed, consisting of protein, RNA, and DNA.”
What is Centrioles?
● Centrioles is situated in the cytoplasm close to the nucleus
● Needed during cell division
● Not visible until the cell is about to divide
“Centrioles are paired barrel-shaped organelles located in the cytoplasm of animal cells near the nuclear envelope. Centrioles play a role in organizing microtubules that serve as the cell’s skeletal system.”
What is the function of Centrioles?
The function of centrioles is to connect to the chromosomes to make sure the correct amount of DNA is present in the new cells formed. They help determine the locations of the nucleus and other organelles within the cell.
What are the two different types of Cell Division and their function?
- Mitosis
- Meiosis
What is the function of the two different types of Cell Division?
Meiosis - gives rise to sperm cells and egg cells (gametes/sex cells).
Meiosis gives cells which are found in the testes (for males which are referred to as sperms). They also give cells which are found in the ovaries (for females which are referred to as eggs).
● First two steps are similar to mitosis
● Third step - you end up with four new cells with half the full number of chromosomes (23).
Mitosis - gives out normal cells
Mitosis - each pair of chromosomes make a copy of themselves (they duplicate). Cells start to divide. Two new ‘daughter cells’ (identical to parent). Exact same number of chromosomes formed.
What is cell membrane?
The cell membrane, also called the plasma membrane, is found in all cells and separates the interior of the cell from the outside environment. The cell membrane consists of a lipid bilayer that is semipermeable. The cell membrane regulates the transport of materials entering and exiting the cell.
Structure – Bilipids Layer (double fate) – two layers of fats with protein molecules embedded in it. It has a head, and it has a tail. The head is a phosphate molecule (it likes water and its described as being hydrophilic) and the tail is made up of fatty acid (it hates water, and it is described as hydrophobic).
They allow substances to move in and out of the cells.
It gives the cells its structure
It maintains the environments inside the cell
How does the cell membrane transform substances across?
There are two ways the cell membrane transforms substances across, which are:
Passive transport – doesn’t require energy. Simple diffusion facilitated diffusion osmosis (some substance pass across the membrane by diffusion or osmosis). For example, oxygen, carbon dioxide and fatty acid, they pass through without any energy being needed. Water molecule passes crosses the membrane by osmosis.
Active transport – do require energy. Bigger (macromolecules) for example, carbohydrate, amino acids, ions any charged particles are carried across by active transport. They carry them across the channel and the inside. They cross through the protein molecules through the channels requiring energy.
Mention substances passes through channels (bigger molecules go through bigger active channels. Mention Diffusion and osmosis
What are the function of cell membrane?
The cell membrane gives the cell its structure and regulates the materials that enter and leave the cell. It is a selective permeable barrier, meaning it allows some substances to cross, but not others. Like a drawbridge intended to protect a castle and keep out enemies, the cell membrane only allows certain molecules to enter or exit.
Cell membranes consist of a double layer. There are two parts of the molecule (the head and the tail). There are different types of protein embedded
Cell membranes protect and organize cells. All cells have an outer plasma membrane that regulates not only what enters the cell, but also how much of any given substance comes in.
Where are the centrioles found in the cell?
They are found in the cytoplasm close to the nucleus.
“Centrioles are paired barrel-shaped organelles located in the cytoplasm of animal cells near the nuclear envelope. Centrioles play a role in organizing microtubules that serve as the cell’s skeletal system. They help determine the locations of the nucleus and other organelles within the cell.”
What is the Golgi apparatus and its function?
A Golgi body, also known as a Golgi apparatus, is a cell organelle that helps process and package proteins and lipid molecules, especially proteins destined to be exported from the cell. Named after its discoverer, Camillo Golgi, the Golgi body appears as a series of stacked membranes.
They pack, store and modify (change) protein and lipid.
What are the three differences between the process of mitosis and meiosis?
Mitosis - gives out normal cells. Each pair of chromosomes make a copy of themselves (they duplicate). Cells start to divide. Two new ‘daughter cells’ (identical to parent). Exact same number of chromosomes formed.
Meiosis - gives rise to sperm cells and egg cells (gametes/sex cells). Meiosis gives cells which are found in the testes (for males which are referred to as sperms). They also give cells which are found in the ovaries (for females which are referred to as eggs). First two steps are similar to mitosis.
Third step - you end up with four new cells with half the full number of chromosomes (23).
How the process of meiosis does occurs using diagrams?
Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information. These cells are our sex cells – sperm in males, eggs in females. During meiosis one cell divides twice to form four daughter cells.
“Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information. During meiosis one cell divides twice to form four daughter cells. These four daughter cells only have half the number of chromosomes of the parent cell – they are haploid.”
Chromosomes
Chromosomes are made up of DNA (deoxyribonucleic acid).
Identify the function of ribosomes.
Produces proteins/Translates DNA/genetic information from nucleus into making proteins
