unit 1 Flashcards
(125 cards)
1
Q
what is a somatic cell
A
any cell in the body other than cells involved in reproduction
2
Q
What are germline cells
A
gametes (sperm and ova) and the stem cells that divide to form gametes
3
Q
How do somatic stem cells divide
A
By mitosis to form more somatic cells
4
Q
How do germline cells divide
A
by mitosis and then by meiosis
5
Q
What does division by mitosis do
A
Produce more germline stem cells
6
Q
How can a nucleus of a germline stem cell divide
A
by mitosis to maintain the diploid chromosome number
7
Q
how many pairs of homologous chromosomes do diploid cells have
A
23
8
Q
what does division by meiosis do
A
produces haploid gametes
9
Q
How does the nucleus of a germline stem cell divide
A
by meiosis. it undergoes two divisions, firstly separating homologous chromosome and secondly separating chromatids
10
Q
How many single chromosomes do haploid gametes contain
A
23
11
Q
what is cellular differentiation
A
The process by which cell expresses certain genes to produce proteins characteristic for that type of cell
12
Q
what does differentiation allow a cell to do
A
Carry out specialised functions
13
Q
What are the two types of stem cells
A
Embryonic and tissue
14
Q
What can cells in the very early embryo do
A
differentiate into all the cell types that make up the individual ,and therefore are pluripotent
15
Q
What can all the chain is an embryonic stem cells do
A
be switched on ,so the cells can differentiate into any type of cell
16
Q
What are tissue stem cells involved in
A
They are involved in the growth ,repair and renewal of the cells found in that tissue
17
Q
What are tissue stem cells
A
they are multi potent as they can differentiate into all of the types of cell found in a particular tissue type
18
Q
What can blood stem cells located in bone marrow do
A
they can give rise to red blood cells platelets phagocytes and lymphocytes
19
Q
What are the therapeutic uses of stem cells
A
They are used in corneal repair on the regeneration of damaged skin
20
Q
What can stem cells from the embryo do
A
they can sell for new under the right conditions in the lab
21
Q
What does stem cell research privide
A
provides information on how cell processes such as cell growth ,differentiation and gene regulation work
22
Q
What does stem cell research involve
A
Stem cells being used as model cells to study how diseases develop or being used for drug testing
23
Q
What are the ethical issues of using embryonic stem cells
A
use of embryonic stem cells can offer effective treatments for disease and injury . however, involves destruction of embryos
24
Q
Why do cancer cells divide excessively
A
because they do not respond to regulatory signals
25
What happens when cancer cells divide excessively
This results in a massive abnormal cells called a tumour
26
How are secondary tumours are formed
Cells within the body may fail to attach to each other , spreading through the body where they may form secondary tumours
27
what is the structure of DNA
* contains nucleotides (deoxyribose sugar, phosphate and base).
* Has a sugar-phosphate backbone
* The base pairing (adenine- thymine and guanine- cytosine) Held by hydrogen bonds and has double-stranded anti-parallel structure
* DNA contains a deoxyribose and phosphate at 3’ and 5’ ends of each strand, forming a double helix
* The base sequence of DNA forms the genetic code
28
What is DNA replicated by
A DNA polymerase
29
What does DNA polymerase need to start replication
primers
30
what is a primer
A short strand of nucleotides which binds to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides
31
what does DNA polymerase do
adds DNA nucleotides, using complimentary base pairing, to the deoxyribose (3’) end of the new DNA strand which is forming
32
what forms two template strands
when DNA is unwound and hydrogen bonds between bases are broken
33
DNA polymerase can only our DNA nucleotides in one direction, what does this result in
The leading strand being replicated continuously and the lagging strand replicated in fragments
34
What are fragments of DNA join together by
ligase
35
What does PCR stand for
polymerase chain reaction
36
What does polymerase chain reaction do
Apple far is DNA using complimentary primers for specific target sequences
37
what are primers in PCR
Short Straughns of nucleotides which are complimentary to specific target sequences up to ends of the region of DNA to be amplified
38
what is stage 1 of PCR
DNA is heated to between 92° and 98°C to separate the strands
39
what is stage 2 of PCR
DNA is then cooked to between 50° and 65°C to allow primers to bind to target sequences
40
what is stage 3 of PCR
DNA is heated again but to between 70° and 80°C for heat-tolerant DNA polymerase to replicate the region of DNA
41
What are the practical applications of PCR
PCR can amplify DNA to help solve crimes, settle paternity suits and diagnose genetic disorders
42
what does gene expression involve
the Transcription and translation of DNA sequences
43
what are the three types of RNA
mRNA (messenger RNA), tRNA (transfer RNA) and rRNA (ribosomal RNA)
44
What is the structure of RNA
• RNA is single-stranded and is composed of nucleotides containing ribose sugar, phosphate and one of four bases: cytosine, guanine, adenine and uracil
45
what is mRNA
```
Messenger RNA (mRNA)
carries a copy of the DNA code from the nucleus to the ribosome
```
46
where is mRNa transcribed from
from DNA in the nucleus and is translated into proteins by ribosomes in the cytoplasm
47
what is each triplet of based on the mRNA molecule called
a codon and codes for a specific amino acid
48
what does each tRNA molecule do
carries its specific amino acid to the ribosome
49
why does tRNA fold
due to complementary base pairing
50
what is an anticodon
an exposed triplet of bases
51
what do tRNA molecules have
an anticodon at one end and an attachment site for a specific amino acid at the other end
52
what forms the ribosome
rRna and proteins
53
RNA and the process of transcription
•RNA polymerase moves along DNA unwinding the double helix and breaking the hydrogens bonds between the bases
• RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairing
•Urcail (instead of thymine) is complementary to adenine
• RNA splicing forms a mature mRNA transcript
the introns of the primary transcript are non-coding regions and are removed
•the exons are coding regions and are joined together to from the mature transcript
•the order of exons is unchanged during splicing
54
what happens during the translation of mRNA
mRNA is translayed into a polypeptide at a ribosome
55
when does translation begin and end
being behind at a start codon and ends at a stop codon
56
how do anticodons bond to codons
by complementary base pairing, translating the genetic code into a sequence of amino acids
57
what joins amino acids together
peptide bonds
58
what can happen due to alternative RNA splicing
different proteins can be expressed from one gene
59
how can different mature mRNA transcripts be produced from the same priamry transcript
depends on which exons are retained
60
what forms polypeptides
amino acids are linked by peptide bonds to form polypeptides
61
what do polypeptide chains fold to form
the three dimensional shapes of a protein, held together by hydrogen bonds and other interactions between individual amino acids
62
what determines a proteins function
their shape
63
what is phenotype determined by
proteins produced as the result of gene expression
64
what affects phenotype
environmental factors
65
what are mutations
changed in the DNA that can result in no protein or an altered protein being synthesised
66
what is a single gene mutation
single gene mutations involve the alteration of DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides
67
what are missense mutations
missense mutations result in one amino acid being changed for another. this may result in a non functional protein or have little effect on the protein
68
what are nonsense mutations
nonsense mutations result in a premature stop codon being produced which results in a shorter protein
69
what is a splice site mutation
splice site result in some introns being retains and/ or some exons not being included in the mature transcript
70
what do nucleotide insertions or deletions result in
frame shift mutations
71
what do frame shift mutations cause
caused all the codons and all the amino acids after the mutation to be changed. this has a major effect on the structure of the protein produced
72
what are the 4 types of chromosome structure mutations
duplication, deletion, inversion and translocation
73
what is a duplication mutation
where a section of a chromosome is added from its homologous partner
74
what is a deletion mutation
where a section of a chromosome is removed
75
what is an inversion mutation
where a section of a chromosome is reversed
76
what is a translocation mutation
where a section of a chromosome is added to a chromosome, not it’s homologous partner
77
what is the genome of an organism
it is it’s entire hereditary information encoded in DNA
78
what is genome made up of
genes and other DNA sequences that do not code for proteins
79
what happens in genomic sequencing
the sequence of nucleotide based can be determined for individual genes and entire genomes
80
what can computer programs be used to identify
base sequences by looking for sequences similar to known genes
81
what are bioinformatics
compute and statistical analyses
82
what is pharmagenetics
the use of genome information in the choice of drugs
83
what is personalised medicine
when an individuals personals genome sequence can be used to select the most effective drugs and dosage to treat their disease
84
what is a metabolic pathway
metabolic pathways are inter grated and controlled pathways of enzyme-catalysed reactions within a cell.
metabolic pathways can have reversible steps, irreversible steps and alternative routes.
85
what can reactions within a metabolic pathway be
anabolic or catabolic
86
what are anabolic reactions
anabolic reactions build up large molecules from small molecules and require energy
87
what are catabolic reactions
catabolic reactions break down large molecules into smaller molecules and release energy
88
what are metabolic pathways controlled by
the presence or absence of particular enzymes and the regulation of the rage of reaction of key enzymes
89
when does induced fit occur
when the active site changed shape to better fit the substrate after the substrate binds
90
what is induced fit
The induced fit model is a model for enzyme-substrate interaction
91
do substrate molecules have a high or low affinity for the active site
high
92
do the subsequent products have a high or low affinity allowing them to leave the actual sight
low
93
how are some metabolic pathways reversible
the presence of a substrate or the removal of a product will drive a sequence or reactions in a particular direction
94
where do competitive inhibitors bind
at the active site preventing the substrate from binding
95
how can competitive inhibition be reversed
by increasing substrate concentration
96
what do non-competitive inhibitors do
bind away from the active site but change the shape of the active site preventing the substrate from binding
97
Can noncompetitive inhibition be reversed by increasing substrate concentration
no
98
when does feedback inhibition occur
when the end product in the metabolic pathway reaches a critical concentration
99
what does the end product inhibit
The end product inhibits an earlier enzyme, blocking the path way, and so prevents further synthesis of the end product
100
what is glycolysis
The breakdown of glucose to pyruvate in the cytoplasm
101
What is ATP required for
The phosphorylation of glucose and intermediates during the energy investment phase of glycolysis
This leads to the generation of more ATP during the energy pay off stage and results in a net gain of ATP
102
what happens to pyruvate in aerobic conditions
pyruvate is broken down to an acetyl groupthat combines with coenzyme forming acetyl coenzyme A
103
What happens during the citric acid cycle
the acetyl group from acetyle coenzyme A combines with oxaloacetate to form citrate
104
what happens during a series of enzyme controlled steps during the citric acid cycle
citrate is gradually converted back into oxaloacetate which results in the generation of ATP and release of carbon dioxide
105
Where does the citric acid cycle occur
in the matrix of the mitochondria
106
What occurs in both glycolysis and the citric acid cycle
dehydrogenase enzyme is remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH
107
what is the electron transport chain
A series of carrier proteins attached the inner mitochondrial membrane
108
Where are electrons passed along
Electrons are passed along the electron transport chain releasing energy
109
what allows hydrogen ions to be pumped across the inner mitochondrial membrane
The energy produced from the electron transport chain
110
What results in the production of ATP
The flow of hydrogen ions back through the membrane protein ATP synthase
111
What combine with oxygen to form water
hydrogen ions and electrons
112
what is ATP used for
to transfer energy to cellular processes which require energy
113
what happens during vigourous exercise
The muscle cells do not get sufficient oxygen to support the electron transport chain
114
Under what conditions is pyruvic converted to lactate
when the muscle cells do not get sufficient oxygen to support the electron transport chain
115
what does the conversion of pyruvate to lactate involve
The transfer of hydrogen from the NADH produced during glycolysis to pyruvate in order to purchase lactate
116
What does lactate being produced do
causes muscle fatigue
117
 What allows respiration to provide the energy to convert locked it back to pyruvate and glucose in the liver
when the oxygen debt is repaid when exercise is complete
118
what are slow twitch muscle fibres
slow twitch muscle fibres contract relatively slowly but can sustain contractions for longer
they are useful for endurance activities such as long distance running, cycling or cross country skiing
119
What can slow twitch muscle fibres rely on
they can rely on aerobic respiration to generate ATP and have many mitochondria, a large blood supply and high concentration of oxygen-storing protein called myoglobin
120
What is the major storage feel of slow twitch muscle fibres
fats
121
what are fast twitch muscle fibres
fast twitch muscle fibres contract relatively quickly over short periods
they are useful for activities such as sprinting or weightlifting
122
What can fast twitch muscle fibres generate
they can generate ATP through glycolysis only and have fewer mitochondria and lower blood supply compare to slow twitch muscle fibres
123
what is the major storage fuel of fast twitch muscle fibres
glycogen
124
what do most human muscle tissue contain
A mixture of both slow and fast twitch muscle fibres
125
What can athletes sure distinct patterns
muscle fibres that reflect their sporting activities
