B1 Flashcards
Use the terms ‘eukaryotic’ and ‘prokaryotic’ to describe types of cells
Animal cells and plant cells are eukaroytic cells. Eukaryotic cells contain a cell membrance, a cytoplasm, a nucleus etc. Bacteria cells are prokaroytic and are much smaller and they have a: cell wall, a cytoplasm, a singular strand of DNA and plasmids.
Describe the features of Prokaryotic cells
Prokaryotic cells are much smaller than eukaryotic cells, have no nucleus, and lack organelles. All prokaryotic cells are encased by a cell wall. Many also have a capsule or slime layer made of polysaccharide.
Use estimations and explain when they should be used to judge the relative size or area of sub-cellular structures
Estimations can be used to estimate the size/ area of subcellular structures that are too small to measure directly. You can use the known size of the cell and work out how many times the subcellular structure fits in the cell and use that to estimate the size/ area of the sub-cellular structure.
Describe what differentiation is, including differeces between animals and plants
Before a cell can carry out its specific role within an organism, it must first develop the correct subcellular structures for the job. It does this in a process called differentiation which produces specialised cells. For animal cells the majority of differentiation happens in the early stages of life.
Define the terms resolution and magnification
Resolution is a measure of the microscope’s ability to distinguish between two points which are close together on an object. If a microscope can clearly distinguish between the two points, it has a good or high resolution. Magnification is the ability to make small objects seem larger, such as making a microscopic organism visible. Resolution is the ability to distinguish two objects from each other. Light microscopy has limits to both its resolution and its magnification.
The formula of magnification
magnification = size of image/size of real object in standard form
how is genetic information stored in the nucleus
Chromosomes carry genetic information in a molecule called DNA. Mitosis ensures that when a cell divides each new cell produced has the same genetic information. The material inside the nucleus of cells, carrying the genetic information of a living being.
describe the process that happens during the cell cycle, including mitosis
A cell cycle is a series of events that takes place in a cell as it grows and divides. A cell spends most of its time in what is called interphase, and during this time it grows, replicates its chromosomes, and prepares for cell division. The stages are called: propahase, metaphase, anaphase, telophase and interphase. In mitosis a cell divides to form two identical daughter cells. It is important that the daughter cells have a copy of every chromosome, so the process involves copying the chromosomes first and then carefully separating the copies to give each new cell a full set. Before mitosis, the chromosomes are copied.
Describe stem cells
Stem cells are cells with the potential to develop into many different types of cells in the body. They serve as a repair system for the body. There are two main types of stem cells: embryonic stem cells and adult stem cells.
Benefits and issues with stem cells
While stem cell therapy has the potential to cure many diseases and injuries, there are also some risks associated with this treatment. For example, there is a risk of rejection by the body’s immune system, as well as a risk of the stem cells turning into cancer cells.
Define “surface area to volume ratio” and how this related to single celled muticellular organisms
The size of their surface, or surface area, defines how quickly they can absorb substances. The size of their volume defines how much of these substances they need. Single celled organisms have a very large surface area to volume ratio, however large organisms on the other hand have a greater volume, with a smaller increase in surface area. Therefore, the rate of diffusion would be too slow in large organism to provide all of the transport.
Describe the process of active transport
Active transport is an energy-driven process where membrane proteins transport molecules across cells, mainly classified as primary or secondary, based on how energy is coupled to fuel these mechanisms.
