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
Polypeptide
A protein, made up of a long sequence of amino acids
Primary transcript
mRNA containing both introns and exons
Give two examples of post-translational modification
- Cutting or combining of polypeptide chains
2. Adding phosphate or carbohydrate groups to the protein
State three ways in which proteins are held in a 3D shape
- Peptide bonds
- Hydrogen bonds
- Interactions between amino acids
Substitution mutation
Replacing one DNA nucleotide with another
Insertion mutation
Adding a nucleotide to a DNA sequence
Deletion mutation
Taking away a nucleotide from a DNA sequence
Missense mutation
Replacing one amino acid codon with another
Nonsense mutation
Replacing an amino acid codon with a stop codon
Splice site mutation
Creating or destroying the codons for splicing
Frame shift mutation
A mutation that means all codons downstream are out of phase
Deletion chromosome mutation
Loss of a segment of a chromosome
Duplication chromosome mutation
Repeat of a segment of a chromosome
Translocation chromosome mutation
The rearrangement of chromosomal material between two or more chromosomes
Bioinformatics
The use of computer technology to identify DNA sequences
Systematics
Compares the human genome with genomes of other species
Describe the process of PCR
- DNA heated (to separate strands)
- DNA cooled (to allow primers to bind)
- DNA heated (to optimise DNA polymerase which replicates the DNA)
DNA probe
Short, single strands of DNA that detect the presence of specific DNA sequences
Anabolic pathway
A pathway that is biosynthetic (making bigger molecules) and requires energy
Catabolic pathway
A pathway that involves the breakdown of molecules and releases energy
Induced fit
When a substrate approaches the enzyme, it causes a change in the shape of the active site that allows the substrate to bind
Activation energy
The energy required for an enzyme-catalysed reaction to occur
Competitive inhibitor
Binds to the active site, blocking the substrate from binding
Non-competitive inhibitor
Bonds away from the active site but causes a permanent change in the shape of the active site
Feedback inhibition
End product binds to and inhibits an enzyme that catalysed a reaction early in the pathway
State two functions of ATP
- Providing energy
2. Phosphorylation of molecules
What is the end product of glycolysis?
Pyruvate
Name the three stages of aerobic respiration
- Glycolysis
- Citric acid cycle
- Electron transport chain
What happens in the energy investment stage of glycolysis?
ATP is used up
What happens in the energy pay-off stage of glycolysis?
ATP is produced
Name an enzyme in glycolysis that produces an intermediate substance in an irreversible step
Phosphofructokinase
How is acetyl co-enzyme A produced?
Pyruvate»_space; acetyl
Acetyl + co-enzyme A»_space; acetyl co-enzyme A
How is citric acid produced?
oxaloacetate + acetyl co-enzyme A»_space; citric acid
Describe what happens during the citric acid cycle
- Citric acid is produced
- ATP is produced
- Carbon dioxide is released
- NADH/FADH is produced
- Oxaloacetate is regenerated
Name the enzyme that removes hydrogen ions and electrons from molecules
Dehydrogenase
Name the two co-enzymes that pick up hydrogen ions and electrons
- NADH
2. FADH2
How is ATP made in the electron transport chain?
- High energy electrons are used to pump hydrogen ions across a membrane.
- The hydrogen ions flow back through the membrane using the protein ATP synthase.
- TP is synthesised.
What is the final electron acceptor in aerobic respiration?
Oxygen
Name five respiratory substrates
- Glucose
- Starch
- Glycogen
- Fat
- Protein
What is meant by ‘conservation of resources’?
ATP is only made when needed
What is the function of creatine phosphate?
It breaks down to release creatine and phosphate that is used to convert ADP to ADP
Describe what happens in anaerobic respiration.
- Hydrogen from NADH is added to pyruvate to become lactic acid
- This regenerates NAD which is needed for ATP production
Which type of muscle fibre is associated with aerobic respiration?
Slow twitch
Which type of muscle fibre has lots of mitochondria?
Slow twitch
Which type of muscle fibre does not have a good blood supply?
Fast twitch
What type of events are fast twitch muscle fibres best for?
Bursts of activity (eg sprinting, weight lifting)
