Biology Chapter 1

Front 1

What are the key components to Cell Theory?

Back 1

1. All living organisms are composed of cells.

2.Cells are the smallest and most basic unit of life.

3.Cells can only arise from pre-existing cells

Front 2

What is the formula to calculate the magnification of cell size?

Back 2

magnification= size of image / actual size of specimen

Front 3

What are unicellular organisms?

Back 3

Unicellular organisms only consist of one cell that can carry out all functions of life in that cell. They carry out at least seven functions of life: Nutrition, Metabolism, Growth, Response, Excertion (getting rid of waste products),Homeostasis, Reproduction. An example of a unicellular organism is the Paramecium cell.

Front 4

Explain limitations on cell size

Back 4

Surface are to volume ratio is important in the limtiation of cell size because if the ratio is too small, then substances will not enter the cell as quickly as they are required and waste products will accumulate because they are produced more rapidly than they can be excerted.

It is also important in relation to heat production and loss. If the ratio is too small then cells may overheat because the metabolism produces heat faster than it is lost over the cell's surface.

Front 5

What are multicellular organisms?

Back 5

Organisms consistinf of a single mass of cells, fused together, are multicellular. In multicellular organisms different cells perform different tasks. Multicellular organisms have properties that emerge from interaction of their cellular components.

Front 6

Explain cell differentiation in multicellular organisms.

Back 6

Specialized tissues can develop by cell diffferentiation in multicellular organisms. When the different cells perform different functions in the organism, it is called division of labour. Often a group of cells specialize in the same way to perform the same function, and this is what we call tissue. By becoming specialized, the cells in a tissue can carry out their role more efficiently than if they had many different roles. The development of cells in different wyas to carry out specific functions is called differentiation.

Front 7

Explain the relationship between gene expression and cell differentiation.

Back 7

Differentiation involves the expression of some genes and not others in a cell's genome. This is because there are many different cell types in a multicellular organism but they all have the same set of genes. For example, the 220 cell types in the human body have the same set of genes, despite arge differences in their structure and activities. Hence, all cells do not require the entire set of genes in their multicellular organism to function, and when a gene is being used by a cell, it is said that the gene is being expressed.

Front 8

What are stem cells?

Back 8

Stem cells have the capacity to divide and differentiate along different pathways necessary in embryonic development. This property also makes them suitable for theurapeutic uses. Stem cells have two key properties that have made them one of the most active areas of research in biology and medicine today.

1. Stem cells can divide again and again to produce copious wuantities of new cells. They are therefore useful for growh of tissues or the replacement of cells that have been lost or damaged.

2. Stem cells are not fully differentiatied. They can differentiatie in different ways, to produce differnt cell types.

Front 9

What are some theurapeutic uses of stem cells?

Back 9

Stem cells are used in different ways to treat diseases, one strategy involving embryonic stem cells and one using adult stem cells. Stem cells are used to treat f.eg. Stargardt's disease. Stargardt's disease is a genetic disease that develops in children between the ages of six and twelve. Most cases are due to recessive mutation of a gene called ABCA4. This causes a membrane protein used for active transport in retina cells to malfunction, which leads to a worse vision, even blindness. To treat this disease, they use embyonic cells developed into retina cells.

Front 10

What are some ethical issues when it comes to stem cell research?

Back 10

Stem cell research has been very controversial, and many ethical objections have been raised. For example when extracting stem cells from embryos, the embryo often then dies. This is considered wrong by some who believe human life begins already at a fertilized egg and is worth just as much as a new-born baby.

Front 11

What are Prokaryotic Cells?

Back 11

There are two types of cells; prokaryotic and eukaryotic. First cells to evolve were the prokaryotic cells and exist today as bacteria. They have simple structure, and unlike eukaryotic cells, prokaryotic cells are not compartmentalized. They have no nucleus, mitochondria or any other membrane-bound organelles within their cytoplasm

Front 12

Know how to draw and recognize a prokaryotic cell.

Back 12

The prokaryotic cell contains pili, flagellum, cell wall, plasma membrane, cytoplasm, 70S ribosomes, and a nucleoid (the region containing naked DNA)

Front 13

Explain Binary Fission.

Back 13

Binary Fission is the way prokaryotic cells divide. This process simply means splitting into two, as the bacterial chromosomes are replicated so there are two identical copies. After the replication, the the chromosomes are moved to opposite ends of the cell and the wall and plasma membrane are then pulled inwards so the cell pinches apart to form two identical cells.

Front 14

What is an Eukaryotic cell?

Back 14

Eukaryotes include animal cells and plant cells. Unlike prokaryotic cells, they have a nucleus, and their organelles are protected by a membrane. This is called compartmentalization, and the advantage of that is that the enzymes and substrates used in a process can be concentrated in a small area, with pH and other conditions being at their optimum levels and with no other enzymes that might disrupt the process.

Front 15

Know how to draw and recognize an Eukaryotic cell.

Back 15

An Eukaryotic cell contains; plasma membrane (or cell wall), vesicles, cytoplasm, mitochondrion, lysosome, golgi apparatus, rough endoplasmic reticulum, nucleus, chloroplast.

Animal and plant cells tend to have some differences, be aware of those.

Front 16

Know how to draw and label membrane structure.

Back 16

The membrane structure contains; the basic phospholipid layer with hydrophilic phosphate heads and hydrophobic hydrocarbon tail, integral proteins embedded in the phospholipid bilayer, glycoprotein, peripheral protein on the surface of the memrane, protein pump, and cholesterol.

Front 17

What are phospholipids?

Back 17

They're the basic component of all biological membranes. Phospholipid molecules are amphipathis, which means that part of the molecule is attracted to water (hydrophilic) and part is not attracted to water (hydrophobic).

Front 18

What is cholesterol?

Back 18

Cholesterol is a component of animal cell membranes. Most of the cholesterol molecule is hydrophobic, but just like phospholipids, cholesterol has one hydrophilic end so that it fits between phospholipids in the membrane.

Cholesterol restricts the fluidity and the permeability of the membrane to hydrophilic particles such as sodium ions and hydrogen ions.

Front 19

What are membrane proteins?

Back 19

Membrane proteins are diverse in structure, function and position in the membrane. They can be used for cell-to-cell communication, or transporting substances in and out of the cell. There are different types of membrane proteins; integral proteins, peripheral proteins and glycoprotein.

Front 20

Explain Diffusion.

Back 20

Diffusion is the passive movement of particles from a region of higher concentration to a region of lower concentration, as a result of randdom motion of particles. Diffusion can occur across membrane if there is a concentration gradient and the membrane is permeable to the particle.

Front 21

Explain facilitated and simple diffusion.

Back 21

Facilitated diffusion - Some substances are unable to pass between the phospholipids, and to allow these substances to diffuse through membranes, channel proteins are used.

Simple diffusion - Membranes that allow some substances to diffuse but not others, which means that they're partially permeable. Some of these substances move between the phospholipid molecules in the membrane.

Front 22

What is Osmosis?

Back 22

Osmosis is the passive movement of water molecules from a region of lower solute concentration to a region of higher solute concentration, across a partially permeable membrane. The attractions between solute particles and water molecules are the reason for water moving to regions with a higher solute concentration.

Front 23

Explain active transport.

Back 23

Active transport is the movement of substances using energy from ATP. Active transport can move substances against the concentration gradient (from a region of lower to a region of higher concentration).

Protein pumps in the membrane are used for active transport. Each pump is specific to a substance so that cells can control what is absorbed and what is expelled.

Front 24

Write down and sketch the stages of Mitosis

Back 24

1.Early prophase, 2. Late Prophase, 3. Metaphase, 4. Anaphase, 5. Early Telophase, 6. Late Telophase

Front 25

Explain and sketch the Cell cycle.

Back 25

The cell cycle is a sequence of events between one cell and the next. It has two main phases: interphase and cell division. Interphase is a very active phase in the life ofa cell when many metabolic reactions occur. During interphase the numbers of mitochondria in the cytoplasm increase, as they grow and divide. In plant cells the numbers of chloroplasts increase in the same way. Interphase consists of three phases, the G1 phase, S phase and G2 phase. In S phase the cell replicates all the genetic material in its nucleus, so that after mitosis both the new cells have a complete set of genes.

Front 26

What are cyclins?

Back 26

Cyclins are a group of proteins that are used to ensure that tasls are performed at the correct time and that the cell only moves on to the next stage of the cylcle when it is appropriate. Cyclins bind to enzymes called cyclin-dependant kinases. These kinases then become active and attach phosphate groups to other proteins in the cell.

Front 27

How are tumors formed?

Back 27

The formation of tumors is called oncogenesis, and the process starts with mutations in genes involved in the control of the cell called oncogenes. Mutations have to occur in several oncogenes in the same cell for a tumor to form.