Unit 1 Flashcards
(145 cards)
1
Q
Somatic cells
A
Somatic cells are the cells that make up the human body and are not involved in reproduction
three types of somatic cells are skin cells red blood cells and nerve cells
2
Q
What is the chromosome complement of somatic cells?
A
Each somatic cell is diploid (two sets of chromosomes and contains 23 pairs of homoglous chromosomes )
3
Q
What is produced during mitosis
A
Two identical daughter cells identical to the parent cell
4
Q
What happens during mitosis
A
DNA becomes visible
chromosomes replicate
chromosomes line up at the equator and spindle fibres form
chromosomes are pulled apart to opposite sides of the cell
cytoplasm divides and nucleus reforms and two identical daughter cells are formed
5
Q
What are germline cells
A
Germline cells are involved in reproduction this includes the gametes and the cells that produce the gametes
examples of germline cells are sperm cells and egg cells
6
Q
What is a gamete
A
The term given to sex cells such as sperm cells or egg cells
7
Q
What does diploid mean
A
The term given to a sale containing two sets of chromosomes
8
Q
What does homoglous mean
A
The term used to describe two chromosomes which have the same genes
9
Q
What is meiosis
A
A form of cell division where by four genetically different haploid gamete cells are produced
10
Q
What is haploid
A
The term given to a sale containing one set of chromosomes (half the genetic information of the parent cell)
11
Q
What cells divide by mitosis
A
Somatic and sometimes germline
12
Q
What cells divide by meiosis
A
Germline cells
13
Q
What is differentiation
A
The process by which an unspecialised cell adapts to a particular function. Only genes related to the function will be expressed
14
Q
What are stem cells
A
Stem cells are unspecialised cells that have the ability to reproduce into a rage of specialised cells
15
Q
Why are embryonic stem cells used more in research
A
They can become any type of cell
16
Q
Why do adults have stem cells
A
To help with growth and repair
17
Q
What is pluripotent
A
Embryonic stem cells can divide into any type of cell to form the embryo, they are pluripotent
18
Q
What is multipotent
A
Tissue stem cells can produce a limited range of cell types, they are multipotent
19
Q
What do bone marrow stem cells produce
A
Red blood cells
White blood cells (phagocytes and lymphocytes)
Platelets
20
Q
What research is carried out on stem cells
A
Investigate cell processes such as growth, gene regulation and differentiation or used as model cells for drug testing and disease development studies
21
Q
What are therapeutic uses of stem cells
A
Bone marrow transplants for leukaemia
Skin grafts for burn patients
Cornel repair can restore eyesight
22
Q
What are some ethical issues with stem cells
A
Stem cells may come from an embryo which destroys it however it can create effective treatments
23
Q
What are cancer cells
A
They do not respond to regulatory signals
They divide excessively to produce a mass of abnormal cells called a tumour
24
Q
What is metastasis
A
When the cancer cells fail to attach to each other and they spread throughout the body causing secondary tumors
25
What are nucleotides made of
A Phosphate, base and deoxyribose sugar
26
What are nucleotides made of
Phosphate
A bade
Deoxyribose sugar
27
How many carbon atoms are in deoxyribose sugar
5
28
What are the 4 different types of nucleotides
Adenosine
Thymine
Cytosine
Guanine
29
What are the base parings
Adenine and thymine, cytosine and guanine
30
What are bases adjacent to each other held together by?
Weak hydrogen bonds
31
What is are DNA strands held together by?
Sugar phosphate bonds
32
What does a DNA strands 3' end have?
A deoxyribose sugar
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What does a DNA strands 5' end have?
Phosphate
34
Where can nucleotides be added?
The 3' end
35
The two strands of DNA in a double helix are said to run ...... to each other
Anti parallel
36
What is the first stage of DNA replication?
DNA molecule unwinds the double stranded gelix and unzips the hydrogen bonds
37
What is the second stage of DNA replication?
DNA primers (a few nucleotides long) join to complete the sequences on the open DNA strands
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What is the third stage of DNA replication?
DNA polymerase uses the primers as a starting point for adding new bases to the 3' and joins them with sugar phosphate bonds
39
What is the fourth stage of DNA replication?
DNA ligase joins all of the fragments (primers + new pieces of DNA strand) toggle to make the new double strand
40
What is the fith stage of DNA replication?
Both new double stranded DnA molecules twist back into the helical shape
41
What is PCR
Polymerase chain reaction is a technique that replicates short sections of DNA quickly
It is an in vitro process (outside the body)
42
What is a primer
A piece if single stranded DNA complementary to a specific target sequence at the 3' end of the strand to be replicated
43
What is the first step of PCR
DNA is heated to between. 92-98°C to separate the DNA strands
44
What is the second step of PCR
DNA is cooled to between 50-64°C to allow primers to bind to target sequence
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What is the third stage of PCR
DNA is heated again to between 70-80°c to allow heat tolerant DNA polymerase to replicate the DNA
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What is step 4 of DNA
Repeated cycles of heating and cooling amplify the region of DNA
47
What is gene expression
Gene expression is the process by which specific genes are activated to produce a required protein
48
What 3 types of RNA are needed for transcription and translation
mRNA
tRNA
rRNA
49
What it RNA
A nucleic acid with a similar structure to DNA
RNA is a singular strand
The nucleotides contain a ribose sugar, a phosphate and a base
50
What are the four bases in RNA
Adenine, Uracil, Guanine and Cytosine
51
Where is mRNA made
It is transcribed in the nucleus
52
What is mRNA used for
Carrying a copy of DNA from the nucleus to the ribosomes where it is translated into protein
This is called transcription
53
What is tRNA
tRNA is folded due to complementary bases within the strand
Each molecule can carry one specific amino acid from the cytoplasm to the ribosomes
They have an attached site
54
What are ribosomes made of
Protein and ribosomal RNA
55
What is a codon
Every triplet of based in RNA is called a codon. Each codes for a specific amino acid
56
What is an an anticodon
Each tRNA molecule has 3 based called an anticodon which will match with a complementary codon
57
What is the strand of mRNA produced by transcription called?
A Primary Transcript
58
How many proteins does the primary transcript code for
One, as only one gene is transcribed to form mRNA
59
What are sections that do code for proteins called
Exons
60
What are sections that don't code for proteins called
Introns
61
What is splicing
When the introns are removed and the exons are joining tough to form mature transcript DNA
62
After the primary transcript is spliced.....
The mature mRNA leaves the nucleus and enters the cytoplasm
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Summarise Transcription
DNA unwinds and RNA polymerase breaks hydrogen bonds
Free RNA nucleotides pair with DNA based (C-G-A-U)
Sugar-phosphate bonds form between RNA nucleotides
This requires ATP and the enzyme RNA polymerase
Introns are removed to form the mature mRNA transcript
mRNA leaves the transcript
64
What are the requirements for transcription
DNA Template
Free RNA Nucleotides
Enzymes (RNA polymerase)
ATP
65
What is translation?
Translation of the synthesis of a protein in the form of a polypeptide chain (chain of amino acids) at the ribosomes
66
What does translation start and end with
Translation begins with a start codon and ends with a stop codon
67
What is the purpose of tRNA in translation
Anticodons bind the complimentary codons to translate the genetic code into an amino acid sequence
Each TRNA molecule carries the next amino acid and peptide bonds join them tightly
As the polypeptide chain forms the tRNA molecules leave to collect another amino acid
68
What is the first stage of translation
mRNA takes the DNA in the nucleus to the site of activity- the ribosomes
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What is the second stage of translation
mRNA contains codons and tRNA contains an anti codon. A codon/ anticodon consists of three bases. Codons match up with their complimentary anticodons
70
What is the third stage a translation
The start codon indicates to the tRNA where to add the first amino acid
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What is the stage of translation
tRNA carries a specific amino acid and this results in amino acids lining up. peptide bonds join amino acids to make protein
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What is the fifth stage of translations
Stop codons indicate to tRNA to stop adding amino acids
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What is the sixth of translation
When translation stops polypeptide chain is released from ribosome
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How many proteins can a gene code for
Many
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What is alternative splicing
Different RNA sections are treated as exons and introns resulting in different mature mRNA depending on which exons are retained
76
How are 3-D proteins formed
Polypeptide chains to form the proteins using hydrogen bonds and other interactions between amino acids
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What determines a proteins function
Its shape and structure
78
Do you expression determines the proteins produced and therefore....
Determines the phenotype of the organism
79
What are mutations
Mutations are changes in DNA that can result inno protein or an alternate protein being synthesised
80
What are the three types of Gene mutations
Substitution insertion or deletion of nucleotides
81
What is substitution
Substitution mutation involves a change in one single nucleotide in the DNA sequence of a single gene
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What are the three types of substitution
Missense
Nonsense
Splice site
83
Define missense
One Nucleotide changed which results in one amino acid been changed for another. may result in non-functional protein I or little to no effect on the protein
84
Define nonsense
Replacing an amino acid codon with a premature stop codon. resulted in a shorter protein
85
Define splice-site
Some introns are retained or some exons are removed from mature transcript
86
What two types of mutations can frame shift mutations be
Insertion and deletion
87
What is a chromosome mutation
Chromosome mutations involve a change in sequence or number of genes on a chromosome
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What is a deletion chromosome mutation
A section of chromosomes is removed
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What is a duplication chromosome mutation
A section of a chromosome is added from its homoglous partner
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What is a inversion chromosome mutation
A section of chromosome is reversed
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What is a translocation chromosome mutation
A section of chromosome is added to another which is not its homoglous partner
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Why are chromosome mutations usually fatal
They make such a big change
93
What is a genome
It is all the inherited information of an organism that is included in the DNA it is made up of genes and non-coding sequences
94
What are human genomics
The study of the human Genome
95
Sequence of bases can be determined for...
Individual genes and entire genomes
96
What are bioinformatics
Computer programs which can be used to identify DNA base sequences similar to known genes
97
What is required to compare sequence data
Computer analysis and statistics
98
What are pharmacogenetics
The use of a persons genetic information on the choice of drugs
99
What can individuals genetic sequence be used for
To select the most effective drugs and dosages to treat their disease. this is personalised medication
It can also be used to protect a person susceptibility to certain diseases
100
What is an enzyme
A biological catalyst
101
What is the substrate
The substance upon which an enzyme works each anything specific to one substrate
102
What is an active site
The area of an enzyme that extra substrate and with the reaction takes place .
What shape of the active site is specific to one substrate
103
What is activation energy
The energy required a reaction to take place
104
What is a degredation reaction
The breakdown of substrates through enzymes
105
What is a synthesis reaction
Buildup of the substrate through enzymes
106
Name the five properties of enzymes
Enzymes are found in all living cells in
They speed up the rate of reaction
enzymes remain and changed after the reaction so can be reused
enzymes lower the activation energy required for chemical reactions to proceed
The molecule which an enzyme acts on is known as the substrate
107
What are metabolic pathways
Integrated and controlled pathways of enzyme-catalyse reactions within the cell
Repair to the reactions in the body that are linked together can have a reversible and a irreversible steps
Alternative metabolic pathways may exist that can bypass steps in a pathway
108
What is anabolic
Anabolic reactions build large molecules from small molecules and require energy
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What is catabolic
Catabolic reactions break down large molecules into smaller molecules and release energy
110
What are metabolic pathways controlled by
The absence or presence of particular enzymes
| They are also controlled through the regulation of the rate of reaction of key enzymes within the pathway
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What is the active site
The substrate will binds to the active site on the enzyme
112
Substrate show a high....
Affinity (chemical attraction) for the enzymes active site
113
What is is an induced
| Fit
When a substrate molecule into is the active site, the shape of the active site changes slightly to benefit the substrate
114
What happens to the product and the active site of the enzyme
The new product has a Low affinity for the active site of the enzyme and is therefore released
This leaves the enzyme free to repeat the process
115
Describe how some metabolic reactions are reversible
The presence of the substrate and removal of the product to drive the reaction in the forward direction
absence of substrate and build up of the product will drive the reaction in the backwards direction
116
What are the three types of inhibition
Competitive
non-competitive
feedback inhibition
117
What is competitive inhibition
Competitive inhibitors bind to the active site and prevent the substrate from binding
118
How do you reverse
| competitive inhibition
By increasing the substrate concentration making it more likely that the substrate will enter into the active site
119
What is non-competitive inhibition
Inhibitors bind away from the active site to another part of the enzyme
this change the shape of the active site and prevents the substrate from binding
you cannot overcome non-competitive information by increasing the substrate concentration
120
what is feedback inhibition
Occurs when the end product in the pathway which is a critical concentration
the end product then inhibits an earlier enzyme blocking the pathway and preventing further end product from being made
121
What that is phosphorylation?
And enzyme controlled process by which a phosphate group is added to a molecule
For example when Pi is added to ATP to make ATP
122
Name the three stages of arobic respiration
Stage one: glycolysis
stage two :citric acid cycle
stage three: electron transport chain
123
Describe glycolysis
Takes place in the cytoplasm of the cell
does not require oxygen
Glucose (6C) is broken down into intermediate compound then into two molecules of pyruvate 3(C)
net gain of 2 ATP
124
What are the two stages of glycolysis
Energy investment stage energy payoff stage
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Why does glycolysis have an energy investment stage and pay off stage
During the first first phosphorylation 2 ATP molecules are use per glucose molecule, this is the investment stage, and 4 ATP are produced per glucose molecule, that is the payoff stage
126
Dehydrogenase enzymes remove hydrogen ions and electrons... what happens next
These hydrogen ions and electrons are passed to the coenzyme NAD which becomes NADH
127
Name parts of the mitochondria
The folds
Fluid filled matrix
Outer membrane
inner membrane
128
Describe the citric acid cycle
Requires oxygen
pyruvate is converted to Acetyl which combines with coenzyme A to form Acetyl coenzyme A
Acetyl CoA then enters the citric acid cycle and combines with oxaloacetate to form citrate
Citrate is then converted back to oxaloacetate by a series of enzyme controlled reaction is which produce ATP
Dehydrogenase enzymes remove hydrogen ions and electrons which are passed to the coenzyme NAD forming NADH. NADH transfers these to the electron transport chain
129
What gas is released during the citric acid cycle
Carbon dioxide
130
Describe the electron transport chain
Takes place in the folded and inner membrane
The NADH is reduced to NAD
The reduced NAD transfers the high energy electrons to a chain of carriers called the electron transport system
Electrons are passed along the electron transport chain releasing energy in the form of ATP
Energy from electrons is use the pump the hydrogen ions across the inner membrane of the mitochondria
The return flow of hydrogen ions dried ATP synthesis and produces the bulk of the ATP generated by cellular respiration
131
What is the final electron acceptor
Oxygen which combines with hydrogen ions to form water
132
What occurs during vigourous exercise
Cells are not getting enough oxygen to support the electron transport chain
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What happens as a result of cells not getting enough oxygen
Neither the citric acid cycle the electron transport chain can generate ATP required
Only glycolysis is able to produce ATP
This results in pyruvate being converted to lactate
134
The conversion of pyruvate to lactate involves....
The transfer of hydrogen from NADH produced glycolysis to pyruvate in order to produce the lactate
NAD is regenerated to maintain ATP production during glycolysis
135
How many molecules of ATP are produced in total during lactic acid fermentation
Two molecules of ATP per molecule of glucose
136
Describe great oxygen debt
As lactate builds in the muscles it causes fatigue and an oxygen debt builds up
When the oxygen debt is repaid the lactate is converted back in to pyruvate which then enters the aerobic pathway
137
How much ATP is produced when oxygen is present
38
138
How much ATP is produced when oxygen is not present
2
139
What are the other products of the reaction when oxygen is present
Co2 and h2o
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What are the other products of the reaction when oxygen is not present
Lactate
141
Where does respiration take place when oxygen is present
Cytoplasm and mitochondria
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Where does respiration take place when oxygen is present
Cytoplasm
143
What are the two types of skeletal muscle cells?
Fast twitch (type 2) and slow twitch (type 1)
144
Describe slow twitch muscles
Contract slowly but sustained contractions for a long time
good for endurance activities such as long distance running
relies on the aerobic respiration to generate ATP
Have many mitochondria and a large what supply and a high concentration of oxygen storing protein myoglobin
Main fule is fat
145
Describe fast twich muscle cells
Contract quickly but cannot maintain contractions for a long time
are good for short bursts of activity such as sprinting
Have fewer mitochondria and a lower blood supply
Their main storage fuel is glycogen
