Intro Cells Flashcards
(39 cards)
1
Q
The numerous chemical reactions that take place in the body sustain life. All chemical reactions that occur in the body fall under the heading …..
A
Metabolism
2
Q
a) During metabolism large, complex molecules are broken down and energy is released, this is called?
b) The energy released enables chemical reactions to take place that build up the body’s structural and functional components, this is called?
A
a) Catabolism
b) Anabolism
3
Q
- Molecules combine to form cells. The study of cells is called?
- a) Cells are the basic structural and functional units that make up the body. They are surrounded by _________________ and
b) are capable of performing all the activities vital to life, including; ……..? (List 7)
A
- Cytology
- a) Intercellular fluid
b)
- Metabolism,
- Respiration,
- Excretion,
- Responsiveness,
- Growth,
- Repair and
- Reproduction
4
Q
What is Cytoplasm?
A
- Semi-fluid within the cell membrane that
- surrounds the organelles.
- It contains water, ions and many organic compounds including enzymes.
- It is the medium in which many of the cell’s chemical reactions occur.
5
Q
Cell Diagram
Name the Organells:
A
As shown.
6
Q
What is the Cell membrane?
A
- The outer lining that forms the barrier between the cell and the extracellular fluid (fluid outside the cells).
- 20% of extracellular fluid is made up of plasma and so the cell membrane is also referred to as the plasma membrane.
- The cell membrane protects the contents of the cell and regulates the movement of substances into and out of it.
7
Q
What is the Endoplasmic reticulum?
A
- A network of channels running through the cytoplasm.
- It performs many roles including intracellular transport and support.
- It also provides the surface area for many types of chemical reactions. Its surface is often covered with protein-synthesizing ribosomes, forming “rough” endoplasmic reticulum. It is here that most of the cell’s enzyme activity takes place under the influence of ribonucleic acid.
- Endoplasmic reticulum lacking ribosomes is called “smooth” and is involved in lipid (fat) synthesis, including steroids.
8
Q
What is Lysosome?
A
- A single membraned organelle that contains digestive enzymes.
- Lysosomes break down metabolic substances, foreign particles and worn out cell parts.
9
Q
What are Microvilli?
A
- Finger-like projections of the cell membrane
- that increase the surface area for absorption.
10
Q
What are Cilia?
A
- Tiny hair-like structures that protrude from the cell membrane.
- They aid movement and absorption.
11
Q
What is the Golgi-body?
A
- A structure looking similar to a stack of plates.
- Its functions include processing proteins and lipids (fats) and
- controlling the enzyme activity of the endoplasmic reticulum.
12
Q
What is the Nucleus?
A
- Literally means ‘central part’.
- An oval-shaped organelle that contains the chromosomes (the hereditary factors) consisting of deoxiribonucleic acid (DNA).
- controls cellular activities.
- The fluid within the double nuclear membrane is called nucleoplasm. The nuclear membrane has water-filled pores that allow most ions and water-soluble molecules to move between the nucleus and the cytoplasm.
13
Q
What is a Nucleolus?
A
- A part of the nucleus that functions in the synthesis and storage of ribonucleic acid (RNA).
14
Q
What are Mitochondrion?
A
- A large double-membraned organelle, also known as the “powerhouse”.
- It is responsible for producing the majority of the cell’s adenosine triphosphate (ATP), which is the energy-carrying molecule, used to capture and store energy.
15
Q
What is a Ribosome?
A
- An organelle in the cytoplasm that may attach to the endoplasmic reticulum.
- It contains ribonucleic acid (RNA) and proteins.
- Ribosomes are the site of protein synthesis.
16
Q
Vacuoles: (not in diagram!)
A
- Membrane-bound organelles in cells
- that frequently function as temporary storage.
17
Q
Vesicles: (not in diagram!)
A
- Small secretory bladders or sacs situated at the cell membrane.
- They secrete cellular substances.
18
Q
Centrosomes and Centrioles:
A
- A centrosome is a dense area of cytoplasm near the nucleus.
- It has a part to play in cell division.
- The centrosome contains a pair of cylindrical structures called centrioles.
- Each centriole contains clusters of microtubules.
- Microtubules are made of protein and they provide support, structure and transportation.
19
Q
Metabolism & Respiration
All metabolic reactions take place in cells. The energy released when complex molecules are broken down is used to build up the body’s structural and functional components. These vital metabolic reactions require fuel ((food… The food we eat is broken down during the digestive process and the nutrients are absorbed from the intestine into the blood.) Tiny molecules (including glucose) derived from the food eventually pass from the blood into the intercellular fluid and are then transported through the cell membrane into the cell. ) and oxygen is inhaled into the lungs, absorbed into the blood and is then passed into the intercellular fluid.
- What is this called
- and how is the equation expressed?
A
- “Aerobic cellular respiration”
- Glucose + Oxygen = Energy + Carbon Dioxide + Water
When the oxygen arrives in the cell, the oxygen and the glucose react to produce energy, carbon dioxide and water.
20
Q
Excretion
A
- Wastre products from metabolic reactions, such as carbon dioxide, have to be excreted from the cell.
- If not, the cell becomes toxic.
- Waste products from the cell are transported through the cell membrane into the intercellular fluid. They then make their way into the blood.
21
Q
Both respiration and excretion require the movement of substances into and out of the cell. The ability for substances to move between the cell and the intercellular fluid is vital for….
A
Homeostasis
22
Q
The movement of solutes through the cell membrane can only occur because it is semi-permeable. Expand:
A
- This means that it is not impenetrable and
- can selectively allow some substances through.
23
Q
The main ways by which substances pass through the semi-permeable cell membrane are:
A
- Diffusion
- Osmosis
- Filtration
- Active Transport
24
Q
Diffusion
A
- When there is a greater concentration of a solute on one side of the cell membrane than the other, the solute may move passively (without using energy) through the cell membrane until the concentration on either side of the membrane is equal.
- This process of solutes moving from an area of high concentration to an area of low concentration is called diffusion. Diffusion is dependent on the size of the solute’s molecules.
- If the molecules are too large to pass through the cell membrane then clearly diffusion cannot take place. Diffusion of molecules across the cell membrane may be aided by membrane proteins that serve as transporters. This is called facilitated diffusion and is still a passive process.
25
Osmosis
* Osmosis is the process in which **water** passes passively through a semi-permeable membrane to **equalise the concentration of dissolved substances**.
* The water moves from the side of low chemical concentration to the side of high chemical concentration. Osmosis therefore allows the chemical levels inside and outside of the cell to be equalised when the chemicals themselves are too large to diffuse through the cell membrane.
26
Filtration
* Substances may be forced across the cell membrane by **gravity or water pressure**.
* This passive process always forces substances from the area of **higher pressure into the area of lower pressure**.
27
Active Transport
* Some substances cannot move through the cell membrane passively. They **require energy** to move into or out of the cell. Active transport is the term given to the ways in which substances can, with the use of energy, pass into and out of the cell.
* Some substances are **pushed or pumped through** and others are literally “**carried**” across.
28
Sometimes the cell membrane wraps around solid particles or fluid and literally engulfs them into the cell. This occurs by one of the following active processes:
1. Phagocytosis
2. Pinocytosis
29
Phagocytosis
* Some cells are capable of "**eating**" a solid particle.
* The cell membrane and cytoplasm extend, causing projections called **pseudopods**.
* These extensions engulf the particle and the pseudopods fuse, effectively encapsulating the particle within the cell.
* Once inside the cell the particle is **digested by enzymes**.
* Phagocytosis plays a role in immunity.
30
Pinocytosis
* Pinocytosis is "**cell drinking**".
* It is similar to phagocytosis but the cell **engulfs droplets of extracellular fluid** rather than solid particles.
* No pseudopods are formed. Instead the membrane folds inwards, forming a **pinocytic vesicle** that allows the liquid to flow inward and then the cell surrounds the liquid. The pinocytic vesicle can then detach from the cell membrane.
* While only certain types of cells are capable of phagocytosis, **most cells can perform pinocytosis**.
31
Sensitivity
* **All cells are sensitive** and therefore have the **ability to respond to a stimulus**.
* This allows them to pick up messages from other parts of the cell or other parts of the body and respond accordingly.
32
Repair Growth & Reproduction
* Cells can **produce proteins** and can therefore **repair themselves** and grow.
* However, they do become irreparably damaged, diseased or worn out and die.
* Growth and repair are largely under the **hormonal control of the endocrine system** but are affected by many other factors including nutrition, environmental influences and disease.
* Billions of cells are lost in an average day. It is therefore vital that new cells are produced to replace the old and to enable growth to occur.
33
Cell division is the process by which cells reproduce themselves. It consists of nuclear division (division of the nucleus) and cytoplasmic division (division of the cytoplasm and organelles). Cytoplasmic division is called ?
**Cytokinesis**. The nucleus and cytoplasm divide to produce new cells.
34
There are 2 main types of nuclear division:
1. Mitosis
2. Meiosis
35
Mitosis
* The cell divides to produce **two identical cells**. Mitosis ensures that the new cells have the same number and kind of chromosome as the parent.
* It is an ongoing process that replaces dead or injured cells and adds new cells for growth.
36
Meiosis
* The **cell divides to produce four cells**, each with **half the genetic complement** of the parent cell.
* Meiosis is the process by which the **gametes** are produced.
37
Mitosis is the nuclear division that occurs in all non-sex cells to produce two identical cells. The chromosomes in the nucleus of the cell first replicate. Each chromosome is then made up of 2 identical **chromatids**, joined at a point called a **centromere**. There are then 4 phases of mitosis:
1. **Prophrase** The chromosomes, that have already replicated to consist of two chromatids, appear to shorten and thicken. The nuclear membrane disintegrates.
2. **Metaphase** The chromosomes align down the centre of the cell.
3. **Anaphase** The chromatids split into two groups, each group containing identical genetic information, and move to opposite ends of the cell.
4. **Telophase** A nuclear membrane forms around each group of chromosomes. During late anaphase or early telophase, the cell membrane begins to indent at opposite sides of the cell.
The opposite sides of the cell membrane eventually make contact, dividing the cytoplasm (cytokinesis) around each new nucleus. The two new identical cells can then split.
38
Mitosis ensures that the new cells have the same number and same kind of chromosome as the parent.
1. Why does Mitosis occur &
2. What is the cell said to be when it's not undergoing mitosis?
1. Mitosis is an ongoing process that replaces dead or injured cells and adds new cells for growth.
2. However, cells are not always in a state of mitosis. They are said to be in **interphase** when they are carrying on their usual processes but not dividing.
39
What is the lowest level of structural organisation?
**Chemical**
It includes all **atoms** (e.g. carbon, hydrogen, oxygen, nitrogen, calcium, potassium, sodium) and **molecules** essential for maintaining life.
