Unit 1 - Human Cells Flashcards
Name two types of human stem cell
Adult stem cell and embryonic stem cell
Give a definition of cellular differentiation
Cellular differentiation is the process by which a cell develops more specialized functions by expressing the genes characteristic of that type of cell
Give two ways that stem cells differ from other body cells
Stem cells are undifferentiated whereas body cells are suited to a specific function
Stem cells can become any cell type of the human body
What is a somatic cell?
A somatic cell is a body cell that divides by mitosis to form more body cells
Give two differences between embryonic and adult stem cells
Embryonic stem cells are pluripotent; they can become any cell type. They are found in embryos.
Adult (tissue) stem cells are found in specific regions; bone marrow, muscles etc. They can only become several cell types from the region of extraction.
By what process do somatic cells divide?
Somatic cells divide by mitosis
When germline cells divide by mitosis what do they form?
They produce more germline cells
When germline cells divide by meiosis what do they form?
They form haploid gametes
In what type of cell would a mutation be passed on to the offspring?
Germline
Give one therapeutic use of stem cells
They can be used therapeutically to repair damaged or diseased organs and tissue. Current uses include corneal and skin grafts.
Give one use of stem cells in research
They can be used as model cells to study how diseases develop or for drug testing
Give one ethical issue concerning the use of stem cells
Is the prevention of suffering more important than the duty to preserve human life? - Embryonic stem cell research forces us to choose between two moral principles; prevent suffering or respect the value of human life?
Give a definition of a tumour
A tumor is a collection of cancer cells produced by excessive, uncontrolled cell division
Give 2 ways that cancer cells are different to other cells
They don’t respond to regulatory systems; target cells are unresponsive or absent
Cancer cells fail to attach to their surroundings unlike normal cells
How is a secondary tumor formed?
Cancer cells fail to attach to their surroundings and spread throughout the body in the bloodstream, forming secondary tumor
Name the 3 components of a nucleotide
A deoxyribose sugar, a phosphate and a nitrogenous base
What type of bonds hold the 2 DNA strands together?
Weak hydrogen bonds
Which end of a DNA strand has a free deoxyribose sugar?
3’ end has a free deoxyribose sugar
Name a molecule other than DNA, that is found in chromosomes
RNA
Name 2 factors essential for the replication of DNA
DNA polymerase and ATP
Name 2 processed involved in turning a DNA double helix into 2 template strands
Transcription and translation
Which end of the DNA strand does DNA polymerase add nucleotides to?
Adds on the 3’ end
Which end has a free phosphate group?
5’ end has a free phosphate
What enzyme joins DNA fragments together during replication?
DNA ligase
What is an organism’s phenotype determined by?
The phenotype of an individual is the result of the proteins produced by the expression of its genes
Are all the genes in a cell expressed?
Only a fraction of the genes in any cell are expressed
Give 2 types of environment factors that influence gene expression
Intracellular and extracellular environmental factors
Give 2 processes that are regulated during control of gene expression
Transcription and translation
Give 3 structural differences between RNA and DNA
DNA nucleotides have a deoxyribose sugar, RNA have a ribose sugar
DNA nucleotides have the bases adenine, thymine, cytosine and guanine
RNA nucleotides have the bases adenine, uracil, cytosine and guanine
DNA is a double stranded molecule
RNA is a single stranded molecule
What is the function of mRNA?
mRNA carries a complementary copy of the genetic code from the DNA in the nucleus to the ribosome in the cytoplasm to be translated
Give 2 components of a ribosome
They are made of protein and RNA
What is the function or tRNA?
Carries specific amino acids to the ribosomes that can be assembled to form polypeptide chains
What enzyme is responsible for the transcription of DNA to form a primary transcript?
RNA polymerase
What DNA bases are complimentary to the RNA bases A, U, C & G?
Adenine + Uracil
Cytosine + Guanine
Give a definition of an intron
a non coding region on a DNA sequence (of a primary transcript)
What process joins together the exons of a primary RNA transcript?
Splicing
Give a definition of an exon
A coding region in a DNA sequence of a primary transcript
Where does translation of mRNA occur?
In the ribosomes in the cytoplasm