Unit 1 Flashcards
Differentiation
Unspecialised cells become specialised
Somatic cell
Body cells that divide by mitosis
Stem cell
Unspecialised somatic cells that can divide to make copies of themselves and/or differentiate into specialised cells
How does a stem cell differentiate into one type of cell rather than another?
Certain genes are switched on and expressed
Name the three components of a nucleotide of DNA.
- Deoxyribose sugar
- Phosphate
- Base
Name the four bases in DNA
- Adenine
- Thymine
- Cytosine
- Guanine
State the base pairing rule
A - T
C - G
What types of bond hold the two DNA strands together?
Hydrogen bonds between the nitrogenous base hold the two strands of DNA together.
Which part of the DNA strand is the 3’ end?
Deoxyribose
What is meant by the term anti-parallel in DNA?
The two sugar-phosphate backbones run in opposite directions
What is a chromosome?
Tightly coiled DNA packaged with proteins
Describe the stages involved in DNA replication
- DNA is unwound and unzipped
- Primer attaches to the exposed bases
- DNA polymerase adds nucleotides
- Nucleotides added at the 3’ end
- One strand copied continuously, the other in fragments
- Ligase enzyme joins the fragments together
Phenotype
A protein produced as a result of the expression of genes
State three differences between DNA and RNA
- DNA has deoxyribose sugar, RNA has ribose sugar
- DNA is double stranded,
RNA is single stranded - DNA has thymine,
RNA has uracil
Name the four main body tissues
- Epithelial
- Connective
- Muscle
- Nervous
What makes up a ribosome?
- rRNA
2. Protein
Describe the stages of transcription
- RNA polymerase unwinds and unzips DNA
- RNA nucleotides bind to complementary bases on DNA
- A-U, C-G
- RNA polymerase joins RNA nucleotides together
- Introns removed
- Exons joined together by splicing
- Primary transcript formed
Describe the stages of translation
- mRNA attaches to ribosome
- mRNA contains codons (3 bases)
- tRNA attaches to a specific amino acid
- tRNA contains an anti-codon
- Anti-codon binds to codon
- Peptide bond forms between amino acids
- Start codon begins protein, stop codon ends it
Multipotent stem cell
A cell that can differentiate into any cell type within that tissue (eg tissue stem cells)
Pluripotent stem cell
A cell that can differentiate into any cell type (eg embryonic stem cells)
Germ line cell
A cell that gives rise to sperm and egg
What two types of cell division do germ line cells carry out?
- Mitosis
2. Meiosis
Name two therapeutic uses of stem cells
- Corneal transplants
2. Skin grafts
Why are stem cells used as model cells?
- To test drugs on
2. To investigate how diseases develop
Tumour
A mass of abnormal cells
If cancer cells fail to attach to each other, they can spread through the body to form…
Secondary tumours
Codon
Three bases on mRNA (code for a specific amino acid)
Anticodon
Three bases on tRNA
Ribosome
Site of protein synthesis
Amino acid
Building block of a protein