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Unit 1 - Human Cells Flashcards

1
Q

Name two types of human stem cell

A

Adult stem cell and embryonic stem cell

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2
Q

Give a definition of cellular differentiation

A

Cellular differentiation is the process by which a cell develops more specialized functions by expressing the genes characteristic of that type of cell

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3
Q

Give two ways that stem cells differ from other body cells

A

Stem cells are undifferentiated whereas body cells are suited to a specific function

Stem cells can become any cell type of the human body

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4
Q

What is a somatic cell?

A

A somatic cell is a body cell that divides by mitosis to form more body cells

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5
Q

Give two differences between embryonic and adult stem cells

A

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.

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6
Q

By what process do somatic cells divide?

A

Somatic cells divide by mitosis

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7
Q

When germline cells divide by mitosis what do they form?

A

They produce more germline cells

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8
Q

When germline cells divide by meiosis what do they form?

A

They form haploid gametes

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9
Q

In what type of cell would a mutation be passed on to the offspring?

A

Germline

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10
Q

Give one therapeutic use of stem cells

A

They can be used therapeutically to repair damaged or diseased organs and tissue. Current uses include corneal and skin grafts.

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11
Q

Give one use of stem cells in research

A

They can be used as model cells to study how diseases develop or for drug testing

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12
Q

Give one ethical issue concerning the use of stem cells

A

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?

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13
Q

Give a definition of a tumour

A

A tumor is a collection of cancer cells produced by excessive, uncontrolled cell division

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14
Q

Give 2 ways that cancer cells are different to other cells

A

They don’t respond to regulatory systems; target cells are unresponsive or absent

Cancer cells fail to attach to their surroundings unlike normal cells

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15
Q

How is a secondary tumor formed?

A

Cancer cells fail to attach to their surroundings and spread throughout the body in the bloodstream, forming secondary tumor

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16
Q

Name the 3 components of a nucleotide

A

A deoxyribose sugar, a phosphate and a nitrogenous base

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17
Q

What type of bonds hold the 2 DNA strands together?

A

Weak hydrogen bonds

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18
Q

Which end of a DNA strand has a free deoxyribose sugar?

A

3’ end has a free deoxyribose sugar

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19
Q

Name a molecule other than DNA, that is found in chromosomes

A

RNA

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20
Q

Name 2 factors essential for the replication of DNA

A

DNA polymerase and ATP

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21
Q

Name 2 processed involved in turning a DNA double helix into 2 template strands

A

Transcription and translation

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22
Q

Which end of the DNA strand does DNA polymerase add nucleotides to?

A

Adds on the 3’ end

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23
Q

Which end has a free phosphate group?

A

5’ end has a free phosphate

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24
Q

What enzyme joins DNA fragments together during replication?

A

DNA ligase

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25
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
26
Are all the genes in a cell expressed?
Only a fraction of the genes in any cell are expressed
27
Give 2 types of environment factors that influence gene expression
Intracellular and extracellular environmental factors
28
Give 2 processes that are regulated during control of gene expression
Transcription and translation
29
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
30
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
31
Give 2 components of a ribosome
They are made of protein and RNA
32
What is the function or tRNA?
Carries specific amino acids to the ribosomes that can be assembled to form polypeptide chains
33
What enzyme is responsible for the transcription of DNA to form a primary transcript?
RNA polymerase
34
What DNA bases are complimentary to the RNA bases A, U, C & G?
Adenine + Uracil | Cytosine + Guanine
35
Give a definition of an intron
a non coding region on a DNA sequence (of a primary transcript)
36
What process joins together the exons of a primary RNA transcript?
Splicing
37
Give a definition of an exon
A coding region in a DNA sequence of a primary transcript
38
Where does translation of mRNA occur?
In the ribosomes in the cytoplasm
39
Explain why tRNA molecules are folded
Because of base pairing and forms a triplet anticodon site and an attachment site for a specific amino acid
40
Name 2 specific sites present on all tRNA molecules?
An anticodon site and an amino acid attachment site
41
How many bases are present in an mRNA codon?
3
42
How many bases are present in a tRNA anti-codon?
3
43
What is the name of the process that uses the mRNA code to produce a protein?
Translation
44
What type of bond hold amino acids together in a protein?
Peptide links
45
Name 2 processes that allow a single gene to code for many proteins
Alternative splicing & post-translational modification
46
Give 2 examples of post-translational modification of proteins
Making changes to the chemical structure of the polypeptide chain or cutting and combining of the chain
47
Give 3 types of forces which hold proteins in their 3D shape
Peptide bonds, hydrogen bonds and interactions between individual amino acids
48
If a gene is mutated what will the consequence be for the protein it codes for?
Mutations of genes result in no protein or an altered protein being expressed
49
Give a definition of a substitution mutation
One nucleotide removed from a DNA sequence and replaced by another with a different base
50
Give a definition of an insertion mutation
An additional nucleotide added into a DNA sequence
51
Give a definition of a deletion mutation
A nucleotide removed from a DNA sequence but not replaced by another this is sometimes called a frame shift mutation
52
Give 3 examples of single nucleotide substitution gene mutations
Missense, nonsense
53
Give 2 examples of frame-shift gene mutations
Insertion and deletion
54
Give 3 examples of chromosome structure mutations
Deletion, duplication and translocation
55
Give a definition of bioinformatics
The use of computers and statistics in analysis of sequence data
56
What type of medicine depends on an understanding of an individuals genetic risk of disease?
Personal medicine
57
What does PCR mean?
Polymerase chain reaction
58
What enzyme is used for replication if DNA during PCR?
Taq polymerase
59
What component of PCR mix ensures that only specific target sequences are replicated?
DNA probes
60
What property of DNA polymerase requires primers to be present in the PCR mix?
DNA polymerase needs an optimum temperature
61
What effect does heating have on the DNA during the PCR cycle?
The DNA becomes denatured
62
What process takes place during cooling in the PCR cycle?
The primers can bind to the separated DNA strands
63
Describe the structure and function of a DNA probe
A short piece of DNA complementary to a target sequence of DNA
64
What property of an individuals DNA allows them to be identified by DNA profiling?
Variable repetitive sequences
65
Are anabolic pathways energy requiring of releasing?
Requiring
66
Are catabolic pathways energy requiring or releasing?
Releasing
67
What modern theory of enzyme activity has replaced the lock and key model?
Induced fit
68
In what way do enzymes affect the activation energy of a reaction?
Enzymes are biological catalysts that speed up the rate of a reaction by lowering the activation energy required for the reactions to proceed
69
Describe how the concentration of an end product can affect the direction of a reaction
If the concentration of an end product is too high feedback inhibition can occur
70
Where on the enzyme does a competitive inhibitor bind?
Competitive inhibitors have a similar structural shape to the normal substrate of the enzyme so can fit in the active site
71
How does a non-competitive inhibitor affect an enzymes active site?
Non-competitive inhibitors have a different structure and so cannot fit the active site but instead they bind to another part of the molecule. This alters the shape of the active site so much so it cannot combine with the substrate molecule
72
Describe feedback inhibition of a metabolic pathway
Feedback inhibition occurs when an end product inhibits the activity of an enzyme that catalysed a reaction earlier in the pathway
73
What is the role of dehydrogenase enzymes in respiration?
They remove hydrogen ions and high energy electrons from intermediates in the citric acid cycle
74
ATP is used to transfer energy in cells. Give another cellular use of ATP?
ATP is a storage molecule for chemical energy
75
What part of the respiratory pathway breaks down glucose to form pyruvate?
Glycolysis
76
Where in the cell does glycolysis occur?
In the cytoplasm
77
Describe the role of phosphofructokinase in glycolysis?
It catalyses an irreversible reaction in the glycolysis pathways which essentially ensures that the pathway is switched on
78
Give another name for the Citric Acid Cycle?
The krebs cycle
79
Where in the cell does the CAC occur?
In the matrix of the mitochondria
80
Name 3 chemicals made by the CAC
ATP, CO2 and citrate
81
Name 2 co-enzymes that can accept hydrogen ions from dehydrogenase enzymes
NAD and FAD
82
Where in the cell does the electron transport chain take place?
The inner membranes of the mitochondria
83
What high energy molecule is released when NADH and FADH2 are oxidized in the electron transport chain?
Electrons
84
What type of ions flow through the membrane protein ATP synthase causing it to make ATP?
Hydrogen ions
85
What is the final acceptor in the electron transport chain?
Oxygen
86
Name 4 substrates for respiration other than sugar molecules
Pyruvate, acetyl coenzymeA, oxaloacetate and amino acids
87
What enzyme in respiration is inhibited by ATP and citrate?
Phosphofructokinase
88
State the function of créatine phosphate in muscle cells
A substance that acts as a reserve of phosphates & energy in muscle and brain cells. It can be broken down rapidly to release phosphate and energy during the first 10 seconds of intense muscular effort
89
Under what conditions do muscles produce lactic acid
In the absence of oxygen during physical activity
90
What type of muscle fibres are best suited to endurance activities?
Slow-twitch muscle fibres
91
What type of muscle fibres are best suited to produce short bursts of activity?
Slow-twitch muscle fibres
92
Which type of muscle fibre contracts more quickly?
Fast-twitch fibres
93
Describe the importance of the regulation of gene expression
Because it conserves cell resources and energy by producing proteins only when they are required
94
Define substitution nonsense
substitution mutation in which a codon is changed to a stop codon, shortening the resulting protein
95
Define missense
A substitution mutation; a single nucleotide change results in a codon for a different amino acid

Higher Human (3 decks)

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