Cell Biology Flashcards
Eukaryotic Cells features
- cell membrane
- cytoplasm
- Genetic material enclosed in a nucleus
Prokaryotic Cells features
-cytoplasm
-A cell membrane surrounded by a cell wall
-The genetic material is not enclosed in the nucleus
It is a unicellular organism
What are plasmids?
A single DNA loop, there may be one or more small rings on this DNA loop
How are sperm cells designed for their job?
Lots of mitochondria on their tails(flagella) to help them swim.
Acrosome on the head contains an enzyme needed to penetrate the egg cell.
Middle section contains lots of mitochondria.
How are nerve cells designed for their job?
Contains an axon-part of the cell that electrical signals travel along
Long axon-increases the distance that electrical signals travel
Myelin-insulates the axon and speeds up the transmission o nerve impulses
Synapses-junctions which allow the impulse to pass one nerve cell to another
Dendrites-increase the surface area to allow other nerve cells to connect more easily
How are muscle cells designed for their job?
Muscle cells contain protein fibres which can change the length
When it contracts they shorten
Contains a lot of mitochondria
How are root hair cells designed for their job?
root hair increase the surface area of the root
They do not contain chloroplasts
They have long projectiles that increase surface area to absorb minerals and water
How are xylem cells designed for their job?
xylem are found in the plant stem and they form long tubes
These tubes carry water and dissolved minerals from the roots of the plant to the leaves
xylem cells
Xylem cells have got no nucleus cytoplasm vacuole or chloroplasts
How are phloem cells designed for their job?
phloem tube’s carry dissolved sugars up and down the plant
phloem vessel cells have no nucleus and only limited cytoplasm
the end walls of the vessel cells have pores called sieve plates
both of these features allow dissolved sugars to move through then cell interior because phloem vessels
cells have got very limited cytoplasm
they haven’t got many mitochondria so each phloem vessel cell has a companion
cell connected by pores
Mitochondria in the companion cell provide energy to the phloem vessel cell
Animal cells features
Cell membrane-selectively permeable and controls substance moving in and out of the cell
Nucleus-control centre
Ribosome-protein synthesis
Mitochondria -the powerhouse of the cell and gives energy for respiration
Cytoplasm-jelly-like fluid where most chemical reactions take place
Plant cell features
Chloroplast-contains chlorophyll which is the site of photosynthesis
Cell wall-made from cellulose which strengthens the cell
Permanent vacuole- contains a fluid called cell sap which gives the plant a shape
Cell Cycle
The cell cycle is a series of stages in the life cycle of a cell
During the growth phase of the cell cycle, the genetic material of the cell (chromosomes) is doubled
Two copies of each chromosome are produced; these initially remain attached to each other with each strand called a chromatid
The chromatids will eventually be divided between the two genetically identical daughter cells that form from the dividing cell
During the growth phase, the number of sub cellular structures (such as ribosomes and mitochondria) also increases
Mitosis
For a multi cellular organism to grow, cells must divide by mitosis to produce two new identical daughter cells
During mitosis, one chromosome from each set is pulled to each end of the cell, and a new nucleus forms around each group of chromosomes
After this, the cytoplasm and cell membranes divide in a process known as cytokinesis. This results in the formation of two genetically identical daughter cells
Cell division by mitosis is important in the growth and development of multi-cellular organisms
For a multi-cellular organism to grow, cells have to divide by mitosis to produce an increase in cell number
Stem cells
A stem cell is an undifferentiated cell which can give rise to more cells of the same type and can differentiate it from other types of cells
unlike embryonic stem cells, adult stem cells cannot differentiate into any other type of cell so for example bone marrow stem cells differentiate to form cells found in our blood such as red blood cells white blood cells and platelets
Problems;
The donors got to be compatible with the patient otherwise the white blood cells produced by the donated bone marrow could just attack the patient’s body
The risk that viruses can be passed from the donor to the patient
Therapeutic cloning
embryo is produced with the same genes as the patient that means that stem cells from the embryo can be transplanted into the patient without being rejected by the patient’s immune system once inside the patient the stem cells can then differentiate to replace cells which are stopped working correctly
Stem Cells in plants
Roots and buds contain meristem tissues
Meristem-can differentiate into any type of plant tissue at any time
We can use it to clone a rare pant to prevent extinction or grow clones of farmers crops.
