Human Cells One Flashcards
(29 cards)
What is a somatic cell ?
Any cell in the body not involved in reproduction
They are diploid (46 chromosomes, 23 homologous pairs)
e.g. muscle, nerve and skin cells
How do somatic cells divide
By MITOSIS
(When a cell makes a genetic copy of itself)
(Maintains diploid chromosome complement so that daughter cells have a complete copy of the genetic info)
What is a Germline cell
Cells that are involved in reproduction
(Diploid, 46 chromosomes, 23 homologous pairs)
Divide by MEIOSIS or MITOSIS
Mitosis of Germline cells
When the nucleus of a Germline stem cells divides by mitosis, the diploid chromosome number is maintained and
MORE GERMLINE CELLS ARE PRODUCED
Meiosis of Germline cells
Produces GAMETES
Gametes are haploid (23 single chromosomes)
1st division- separates the homologous chromosomes
2nd division- separates the chromatids
State what somatic and Germline cells divide by
Somatic- mitosis
Germline-
1. mitosis (produce more diploid Germline)
2. Meiosis (produce haploid gametes)
What is a stem cell
An unspecialised cell that can make new copies of itself or differentiate to make different types of specialised cell
What is a gene
A section of DNA which can be expressed to produce proteins
What is differentiation
When some genes are expressed (turned on) so that the cell can produce the protein and some genes are switched off so that they cannot produce the protein
(It allows unspecialised cells to turn into specialised cells which allows cells to carry out specialised functions)
What are the two types of stem cells?
Embryonic (pluripotent)
tissue (multi potent)
Embryonic stem cells
Derived from a very early embryo (4-5 days old)
PLURIPOTENT
Pluripotent meaning
All genes in these cells CAN be expressed and therefore differentiate into any type of cell
Tissue Stem Cells
Found in one particular tissue type
Involved in the repair and renewal of the cells found in that tissue
Multipotent
Multipotent meaning
Can only differentiate into cells found in their tissue type
Blood Stem cells
Found in the bone marrow
Can only differentiate to produce the different types of blood cells (red, white, platelets)
Therapeutic uses of stem cells
The repair of damaged or diseased tissue
(Bone marrow transplants, skin grafts for burn victims, stem cell grafts for cornea repair)
Reasearch uses of stem cells
Stem cells from the embryo can self renew under the right conditions in the lab. Stem cells are used as model cells to reasearch
-How diseases develop
-to test drugs
-to provide info on how certain cell processes work (cell growth, gene regulation, differentiation)
Ethical concerns of embryonic stem cells
Pro- embryonic stem cells can offer effective treatments for disease and injury
Con- stem cell reasearch using embryonic stem cells results in the destruction of the embryo
Cancer
Cancer cells divide excessively because they do not respond to normal regulatory signals
This creates a mass of abnormal cells called a tumour
Secondary tumours
When cells within the tumour fail to attach to each other they can spread through the body where they can form secondary tumours
What is the structure of DNA
A DNA molecule is made of two strands, each made of repeating units called nucleotides
DNA nucleotides
Deoxyribose sugar (5 carbons)
Phosphate (attached to C5)
Base (attached to C1)
DNA bases
Adenine and Thymine
Guanine and Cytosine
DNA bonds
The strands are held together by hydrogen bonds between complimentary bases
The sequence of bases on DNA forms the genetic code
An individual strand of DNA nucleotides is held together by a strong chemical bond between the phosphate of one nucleotide and the carbon 3 of the deoxyribose sugar on another nucleotide
