Topic 9 Cell Division Flashcards
Explain what a nucleus contains with detail
The nucleus of a cell contains chromosomes made of DNA molecules (chromosomes are sections of DNA that are tightly coiled to form compact structures)
Genes explain in detail what they are and what Carry’s them?
Each chromosome carries a large number of genes. Gene = small section of DNA on a chromosome, which codes for a particular sequence of amino acids, to make a specific protein
Explain in what grouping chromosomes are found in humans and why this is?
In body cells the chromosomes are normally found in pairs - most human body cells have 46 chromosomes (23 pairs; one chromosome in each pair comes from each parent)
bad dont bother
Cells divide in a series of stages called the cell cycle. During the cell cycle the genetic material is doubled and then divided into two identical cells
Name the first stage of the cell cycle and explain what happens ?
Interphase: Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome.
Name the second stage of the cell cycle and explain what happens ?
Mitosis: In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides.
Name the third stage of the cell cycle and explain what happens ?
Cytokinesis: Finally the cytoplasm and cell membrane divides to form two identical cells
Why is cell division by mitosis important?
Cell division by mitosis is important in the growth and development of multicellular organisms
In mature animals cell division is mainly restricted to :
In mature animals, cell division is mainly restricted to repair of damaged tissues and replacement of old/damaged cells. (not “repair” of cells)
Calculate the length of stages in the cell cycle equation:
Number of cells in particular stage / Total number of cells
* length of cell cycle
Meristem tissue in plants can
differentiate into any type of plant cell, throughout the life of the plant
Uses of stem cells from meristems in plants
-Produce clones of plants quickly and economically.
-Rare species can be cloned to protect from extinction.
-Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.
In therapeutic cloning an embryo is produced
with the same genes as the patient. Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment
The use of stem cells has potential risks short summary basically 1 marker
such as transfer of viral infection, and some people have ethical or religious objections
As an organism develops, cells
differentiate to form different types of cells.
As a cell differentiates it acquires different sub-cellular structures to
to enable it to carry out a certain function. It has become a specialised cell
A stem cell is an
undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation
Most types of animal cell differentiate at an —– whereas plant cells
early stage whereas many types of plant cells retain the ability to differentiate throughout life
Stem cells from human embryos and adult bone marrow can be
cloned and made to differentiate into many different types of human cells
Stem cells from adult bone marrow can
form many types of cells including blood cells
Muscle cell function and adaptation :
function: contract and relax in order to move the skeleton, blood or substances in the body
adaptations: many mitochondria to provide energy for muscle contraction
Root hair cell function and adaptation :
Function: Absorb water and mineral ions from the soil
Adaptations: - long ‘finger like’ villi which gives it a large surface area there is a thin wall to reduce the distance that molecules need to move to reach inside of the cell
Sperm cell:
Function: this is the male gamete (sex cell) . It carries genetic information from the father and fertilises the egg cell
Adaptations:-many mitochondria to provide energy for movement of the tail
-the head has a specialised sac of enzymes called acrosome that digests the outer lining of the egg cell
-long tail to help propel the sperm along to the nucleus
-nucleus contains half the number of chromosomes of an adult cell
Xylem cell
function and adaptations
function: to transport water and mineral ions from the roots of the leaves of a plant and provides support for the plant
adaptations: -consist of dead hollow cells- maximising space for water and dissolved substances to be transported
-walls of the xylem vessels are lignified (coated with lignin) this strengthens the xylem
nerve cell
function and adaptions
function; to transmit information(messages) as electrical impulses
adaptations: long- to carry impulses rapidly throughout the body with no gaps between neurones
-insulatory sheath made of fatty myelin- to speed up impulses (100m/s)
-branched endings(dendrites)-make connections with other neurones and allow several different pathways for the impulse
phloem cell
function and adaptations
function: to transport sugars
adaptations: -cross-walls separating cells are called sieve plates erforated by many pores to allow the sap to flow
-companion cells contain many mitochondria which provide energy needed to move sugars around the plant
Issues and practical Problems with stem cells
(don’t mention ethical)
adult stem cells may not be able to be manipulated to produce all cell types. Which limits how adult stem cells can be use to treat diseases. Adult stem cells are also more likely to contain abnormalities due to environmental hazards, such as toxins, or from errors acquired by the cells during replication
Ethical issues
human embryonic stem cell research is ethically and politically controversial because it involves the destruction of human embryos
Embryonic stem cell
ability to differentiate
risks
is there a risk of rejection:
-Can differentiate into all types cell- so can treat many diseases
- risk of transmission of virus
- risk of cancer
- risk of infection during operation transplant
- risk of rejection stem cells.
Adult stem cell therapy
ability to differentiate:
risks:
is there a risk of rejection:
can differentiate into some types of cells to treat less disease
-risk of transmission of virus
- risk of cancer
- risk of infection during operation transplant
risk of rejection need an adult donor can be painful to collect
therapeutic/embryo cloning
-can differentiate into all types of cells so can differentiate into many types of cells
-risk of transmission of virus
- risk of cancer
- risk of infection during operation transplant
- risk of rejection stem cells from embryos can’t give consent or can be taken from amniotic fluid
leaf palisade cell
The function of the palisade cell is photosynthesis. Each palisade cell contains chloroplasts which are used during this process. The palisade mesophyll cells are packed closely together to maximize light absorption for photosynthesis.
adaptations
red blood cells
Red blood cells are adapted for the transport of oxygen. They are small and flexible so they can fit through narrow vessels, have a bi-concave shape which maximises their surface area to absorb oxygen, have a thin membrane so gases easily diffuse through, and contain haemoglobin which binds to oxygen.
specialised cells have a different —– that allows them to ——
structure, carry out their function
