producing new cells (2.1) Flashcards
Identify the part of a cell which controls the process if cell division (mitosis)
The process of cell division (mitosis) is controlled by the nucleus of the cell
what is cell division/mitosis
Cell division/ mitosis is the process by which an organism can increase its cell numbers during growth and repair
State the meaning of the phrase “chromosome compliment”
The chromosome compliment of an organism means the number of chromosomes that its cells contain e.g. human body cells have a compliment of 2n=46 chromosomes
State the meaning of the term “diploid”
The term diploid means two sets of chromosomes found inside a normal body cell
In human cells this is expresses as 2n=46
State the meaning of the term “haploid”
Haploids are found in gamete/sex cells and there is only a single set of chromosomes n=23
State the number of cells produced during the process of mitosis
When a cell undergoes the process of mitosis the cell number will double i.e. one cell will become two cells
Explain the importance of each daughter cell having the same number of chromosomes as the original parent cell
Daughter cells must have the same number of chromosomes as the original parent cell to ensure that they contain a full set of genetic information to be able to function normally
State the term used to identify the two cells formed at the end of mitosis
The two cells formed at the end of mitosis are called daughter cells
State the meaning of the term chromatids
Chromatids are the two identical copies of a chromosome that are formed when a chromosome replicates/doubles immediately before the cell undergoes mitosis. The pair of identical chromatids are held together by the centromere until they are pulled apart by the spindle fibres during mitosis
Identify the equator and spindle fibres in a diagram of a dividing cell
The equator is a term used to describe the middle zone of a dividing cell. This is where the pairs of chromatids will line up and attach to the spindle fibres.
The spindle fibres appear in a dividing cell when the nucleus membrane disappears. The spindle fibres are made of proteins and are anchored at opposite ends of the cell (The north and south poles) When the spindle fibres contract they pull the pairs of chromatids apart and pull the newly formed single chromosomes to the opposite poles
Describe what happens to the chromosomes during the first stage of cell division
During the first stage of cell division/mitosis the chromosomes replicate/double and each chromosome becomes an identical pari of chromatids held together by the centromere
State the definition of a stem cell
A stem cell is an unspecialised/ undifferentiated cell capable of rapid cell division to produce new stem cells (self-renewal) and cells that will then become specialised cells during growth and repair of tissues
Identify two different types of stem cells
Stem cells can be classified as either embryo stem cells or adult/tissue stem cells
Describe stage one of mitosis
- stage one, Original parent cell is preparing for mitosis, the chromosomes are undergoing DNA replication and coiling up to become visible.
Describe stage two of mitosis
stage two, Each chromosome has now doubled to become an identical pair of chromatids
Describe stage three of mitosis
stage three, The nucleus membrane disappears and the spindle fibres appear. The doubled chromosomes migrate to the equator and line up attached to the spindle fibres
Describe stage four of mitosis
Stage four, The spindle fibres start to contract pulling the identical chromatids apart to the opposite poles of the cell
Describe stage five of mitosis
stage five, The spindle fibres disappear and two new nuclear membranes appear around each set of single chromosomes clustered at the opposite poles
Describe stage six of mitosis
Stage six, The cell cytoplasm starts to divide and two new cell membranes form across the centre of the original cell dividing it completely to form two identical daughter cells
Describe where stem cells can be found
Stem cells are found throughout the body in all body tissues
State the two main processes in the body that involve stem cells
Stem cells are involved in growth and repair
Define the term specialisation
Specialisation is the process by which a stem cell becomes specialised/differentiates to carry out a particular function e.g. red blood cells develop a biconcave disc shape, produce haemoglobin and lose their nuclei to allow them to transport oxygen.
State what is formed when organs work together in groups to perform a particular function
When organs work together to perform a particular function this creates a body system e.g. heat and blood vessels create the circulatory system, brain, spinal cord and nerves to create the nervous system ect.
State the functional hierarchy that exists within a multicellular organism
Cells—-Tissues—-Organs—-Systems
Groups of specialised cells working together to carry out a particular function form tissues. Groups of tissues working together form organs. Organs work together to create systems that are designed to carry out specific functions within the body
