Definitions Flashcards
Knowing how to define each and every concept in the stage 2 biology course (131 cards)
1
Q
What is the structure of DNA?
A
DNA is a helical double-stranded molecule with nitrogenous bases and phosphate sugar backbone.
2
Q
How does DNA in eukaryotes differ from the DNA in prokaryotes ?
A
DNA in the eukaryotes is bound to proteins called histones in linear chromosomes and is found in the nucleus. DNA in prokaryotes is circular and is attached to the cell membrane, situated in the cytosol.
3
Q
Describe the structural properties of DNA specifically the base paring and how the weak bonds assist replication.
A
DNA i comprised of a sugar-phosphate backbone with complimentary based pairs in the middle. The bases are paired as A-T and C-G. The weak hydrogen bond between the complimentary based pairs allows for DNA strands to be easily separated.
4
Q
Describe the process of semi-conservative replication of DNA in 3 steps.
A
- Enzymes are used to separate the 2 strands of DNA.
- DNA polymarase joins the free nucleotide to the separated strands of DNA.
- 2 strands are formed with at least half of the old DNA is conserved
5
Q
What is a gene?
A
A gene is a unique sequence of nucleotides that codes for a functional protein or amino acid.
6
Q
Distinguish the difference between exons and introns and identifies the process of elimination of one of them. and
A
Exons are the coding strands of DNA while introns are not. Both are transcribed, but introns get spliced before translation.
7
Q
What is protein synthesis?
A
Protein synthesis is a process that involves transcription of a gene into mRNA and translation of mRNA into amino acid sequence at the ribosomes.
8
Q
What is the site of protein synthesis in eukaryotes?
A
Nucleus, ribosome
9
Q
What is a codon?
A
Codon is a sequence of 3 bases on the RNA strand
10
Q
What is an anti-codon?
A
Anti-codon is a sequence of 3 bases on the tRNA molecule.
11
Q
If the DNA strand that needs to be translated is ACT what is the sequence on the mRNA molecule?
A
ACU
12
Q
If the template strand is ACT then what anti-codon will correspond to it?
A
ACU
13
Q
What does the primary structure depends on?
A
The sequence of amino acids
14
Q
What does the secondary structure depends on?
A
The primary structure.
15
Q
What is the tertiary structure depend on?
A
The secondary and the primary structure.
16
Q
What does the quaternary structure depend on?
A
Which proteins bind together
17
Q
What are proteins used for? Name at least 3.
A
Catalysing the chemical reactions, messages, defence.
18
Q
How do proteins work?
A
Proteins used their specific 3D shape in order to complete task.
19
Q
What can influence the function of the enzymes?
Name and describe 3.
A
pH levels, can denature the proteins. Temperature, can decrease the particle movement and denature the enzymes. Inhibitors, can change the active sight.
20
Q
What influences the rate of enzyme-controlled reaction?
A
The rte of an enzyme-controlled reaction is affected by concentration of reactants and the concentration of the enzymes.
21
Q
What does phenotypic expression depends on?
A
The phenotypic expression of genes depends on factors controlling transcription and translation. These include the products of other genes and the environment.
22
Q
What is methylation?
A
Methylation is a process of attachment of a methyl group to the cytosine and enabling the gene to be translated or transcribed.
23
Q
How can epigenetic changes can lead to human disease?
A
Methylation can lead to suppression of the human suppressor genes thus cancer can develop.
24
Q
What are mutation?
A
Changes in the DNA sequence.
25
What can cause mutations?
Mutations in genes and chromosomes can result from errors in DNA replication or cell division, or from damage by physical or chemical factors in the environment.
26
What can increase the mutation rate?
Ionising radiation, mutagenic chemicals and viruses.
27
What is the difference between the mutation in somatic and germ cells?
Mutations in the somatic cells will only effect that cell and the cells that divide from that cell. Mutations in the germ cells will effect all the cells within an organism.
28
Can DNA be extracted from cells?
Yes. By using different chemicals and bleaches.
29
How can we multiply the DNA? name the process and describe it in 4 steps.
The DNA can multiplied by using PCR. The PCR process involves multiple steps.
1. The DNA is heated to separated.
2. A primer ( small RNA sequence) is attached to prevent the DNA from rejoining.
3. Heat resistant DNA polymarase is attached and the free nucleotides to the separated strands.
4. The DNA is cooled and 2 new strands are formed.
30
How can we determine the base sequence of DNA?
By using the process of electrophoresis.
31
Describe electrophoresis in 4 steps.
1. DNA is amplified with specialy altered nucleotides which signal DNA polymerase to stop sequencing baes.
2. The result is differently sized DNA fragments.
3. Electrical charge is used to transfer pieces across a thick gel (agar).
4. Smaller pieces travel faster then the large once thus a banding pattern occurs.
32
What genetic information is used to create genetic profile?
Short tandem repeats (STRs)
33
What does biotechnology involve?
Biotechnology involves the use of bacterial enzymes, plasmids, and viruses as vectors, and yeasts. Techniques include gel electrophoresis, bacterial transformations, electroporation, microinjection, and PCR.
34
Describe how particular genes can be selected using probes and removed using restriction enzymes.
A restriction enzyme is a protein that cuts a gene at a specific point. The gene is identified by the probe.
35
How can plasmids be used?
Plasmids are small rings of DNA separated from the bacterial chromosomes. The isolated gene can be inserted into the plasmid and reinserted into a pacteria. It is possible that a bacteria with a modified plasmid might allow to produce a product of the gene.
36
What are Ti Plasmids?
Ti plasmids are tumour inducing plasmids and work the same as the normal plasmid.
37
How does viral vectors work?
A gene is inserted into a virus and infects the DNA of the individual.
38
How does a micro-injection work?
You inject the gene into a cell.
39
How does electroporation work?
Electroporation is a process by which an electrical charge is aplied to change the permeability of the cell wall.
40
What is CRISPR and how is it used?
CRISPR stands for clustered regularly interspaced short palindromic repeats. It is made of Cas9 protein and a guide RNA. It is used to cut the genetical code.
41
What is cell theory?
Cell theory states that all living things are made out of cells.
42
What is the function of the cell membrane?
The cell membrane separates the cell cytoplasm from its surroundings and controls the exchange of materials, including nutrients and wastes, between the cell and its environments.
43
Describe why the cell membrane can be described as a 'fluid mosaic'?
The mosaic represents all the different proteins embedded in the structure of the cell membrane. The cell membrane can be described as fluid due to the fact that it is not solid and can change it's shape.
44
What types of cells are there?
Prokaryotic and eukaryotic.
45
State 3 differences between prokaryotic and eukaryotic cells.
Prokaryotic cells are smaller, have low level of internal structure and have circular chromosomes.
46
State at least 3 organelles in a eukaryotic cell.
```
nucleus
nucleolus
mitochondrion
chloroplast
vacuole/vesicle
Golgi body
endoplasmic reticulum (rough and
smooth)
ribosome
lysosome
cytoskeleton.
```
47
Draw a nucleus and label
https://www.google.com/url?sa=i&source=images&cd=&
ved=2ahUKEwit2oedmJjlAhWENI8KHRg9BgIQjRx6BAg
BEAQ&url=https%3A%2F%2Fpaintingvalley.com%2Fnucleus-drawing&psig=AOvVaw1ZTaArQgzMBTpeLnLnpGbj&ust=1571020118483498
48
Draw a mitochondria and label
https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwi718e7mJjlAhWDqI8KHcEcBJcQjRx6BAgBEAQ&url=https%3A%2F%2Fbrainly.in%2Fquestion%2F3039668&psig=AOvVaw21lvjtoof5XyXeNWc4i4Bk&ust=1571020182906450
49
Draw a chloroplast and label
https://www.google.com/imgres?imgurl=https%3A%2F%2Fi.ytimg.com%2Fvi%2F2_ZCgyTCN5U%2Fmaxresdefault.jpg&imgrefurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D2_ZCgyTCN5U&docid=h4--RnbYVvkY6M&tbnid=NJaDq01MLn7VDM%3A&vet=10ahUKEwiI-d3CmJjlAhVq73MBHWS3CtIQMwhxKAEwAQ..i&w=1078&h=720&bih=574&biw=500&q=chloroplast%20drawing&ved=0ahUKEwiI-d3CmJjlAhVq73MBHWS3CtIQMwhxKAEwAQ&iact=mrc&uact=8
50
Draw a golgi body and label
https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwjL6vXdmJjlAhVBnI8KHWMnDr0QjRx6BAgBEAQ&url=https%3A%2F%2Fwww.britannica.com%2Fscience%2FGolgi-apparatus&psig=AOvVaw0izY-TXnV0ekO--vUKTrA8&ust=1571020245456331
51
Compare the animal cells and the plant cell. Give 3 points.
Plant cells have a cell wall and a cell membrane unlike the animal cells. Plant cells have large vacuoles unlike animal cells. Plant cells have chloroplast and animal cells don't
52
What is an autotroph?
Autotrophs are organisms that can produce their own energy through conversion o light.
53
What is a heterotroph?
Heterotrophs are organisms that rely on consuming other organisms for energy.
54
What is the main source of energy for life?
Light
55
What is the chemical formula for photosynthesis?
6CO(2)+6H(2)O = C(6)H(12)O(6)+6O(2) (numbers in brackets is the little ones)
56
What is the chemical formula for aerobic respiration?
C(6)H(12)O(6)+6O(2)=6CO(2)+6H(2)O (numbers in brackets is the little ones)
57
What is the chemical formula for fermentation in animal cells?
C(6)H(12)O(6)=2C(3)H(6)O(3)
58
What is the chemical formula for fermentation in plant cells?
C(6)H(12)O(6)=2C(2)H(5)OH+2CO(2)
59
Which process releases the most energy?
Aerobic respiration.
60
Where is the energy stored in the ATP molecule?
The third bound
61
What is a process of diffusion?
Diffusion is the overall movement of a substance in a fluid region of high concentration of the substance towards regions of lower concentration of the substance.
62
What is a process of facilitated diffusion?
Diffusion using specialised proteins.
63
What is a process of osmosis?
Osmosis is the net movement of solvent across a semi-permeable membrane towards a region of higher solute concentration.
64
What is active transport?
Overall movement of substances in a fluid region of low concentration of substances towards regions of higher concentration.
65
What is endocytosis?
Endocytosis is a process in which vesicles enter the cell.
66
What is exocytosis?
Exocytosis is a process in which vesicles exit the cell.
67
Explain how the structure of a membrane facilitates different processes of movement through it.
Due to the fact that fluid mosaic allows different proteins to be imbeded in order to facilitate different processes and the fluidity allow the cell membrane to reshape and allow the vesicles to enter and exit the cell.
68
What affects exchange of materials across membranes?
1. Surface-area-to-volume ratio. 2. Concentration gradients. 3. The physical and chemical nature of the materials being exchanged.
69
How the structure of internal membranes of mitochondria and chloroplast facilitates some biochemical processes?
Mitochondria has a folded inner membrane allows for greater surface are thus more available space for aerobic respiration. Chlorophyll is stored within the disks of the grana and provides the sight of photosynthesis.
70
Explain why there are multiple steps to a metabolic pathway? (make 3 points)
Each reaction releases heat. Heat can cause a cell to be damaged. Thus there are multiple steps to a metabolic pathway.
71
What can interfere with cell metabolism?
Chemicals
72
Do cells need just appear?
No, they arise from pre-existing cells.
73
What does continuity of life require?
Continuity of life requires the replication of genetic material and its transfer to the next generation through processes including binary , mitosis, meiosis and fertilisation.
74
Why does DNA double before division?
DNA needs to be passed on to the daughter cell thus DNA needs to be replicated so the daughter cell can function.
75
Describe the process of binary fission in 4 steps.
1. The circular chromosome is replicated. 2. The chromosomes attach to the cell membrane. 3. Cell membrane moves to 2 different poles of the cell. 4. The cell pinches off separating the chromosomes resulting in 2 cells.
76
Describe mitosis in eukaryotic cells.
PMAT.
Prophase- The DNA is replicated and condenced into chromosomes.
Metaphase- The chromosomes line up in the middle of the cell and the spindle apparatus attaches to the centromere.
Anaphase- The sister cromatitds get separated.
Telaphase- The cell pinches off. 2 cells are created.
77
What is a diploid cell?
A diploid cell is a cell that contains pairs of homologous chromosomes.
78
Describe meiosis in eukaryotic cells.
PMAT x 2
Prophase I- process of crossing over occurs. The process of random assortment occurs.
Metaphase I- the spindal apparatus attaches to the centromeres of the chromosomes
Anaphase I- spindal apparatus separates homologus in 2 cells. Those cells are now haploid.
Telephase I- 2 cells are created.
Prophase II- the now chromosomes line up in the middle of the cell.
Metaphase II- Spindal apparatus attaches to the centromeres.
Anaphase II- the sister chromatids are separated.
Telephase II- total of 4 cells is created with a haploid number of chromosomes.
79
Explain how random fertilisation restores a diploid number.
2 haploid cells combine together to create one diploid cell.
80
Explain the importance of crossing over and independent assortment in meiosis.
Genetic variation which increases the surviability of the species.
81
Describe the stages in the cell cycle (including checkpoints).
```
G1- growth phase
Checkpoint 1 at G1 phase
S phase- DNA synthesis
G2- growth phase
Checkpoint 2 at G2 phase
Mitosis phase
Checkpoint 3 at metaphase
```
82
What hormones may regulate cell division?
Cdk and cyclin are proteins that controll the cell cycle. Cdk is available through out all the phases while cyclin is available at G1. The two bind to for MPF right before mitosis.
83
How do carcinogens upset normal controls of cell division?
By causing mutations to the genes that code for controlling mechanisms like the p53 gene.
84
Can humans culture cells?
Yes, and different products can be produced.
85
What are the factors for which organisms have tolerance limits? Make 4 points
1. Temperature. 2. Water availability. 3. Blood glucose level. 4. Carbon dioxide concentration in the blood and tissues.
86
In humans what does homeostasis depend on?
The functioning of the nervous and endocrine system.
87
Describe the stimulus response model.
Stimulus-receptor-transmition-effector-response
88
What is the important part of the negative response?
Response inhibits the initial stimulus.
89
What is the nervous system composed of?
CNS and PNS.
90
What are neurotransmitters and what is their role?
Neurotransmitters are proteins that are used to transfer signals across the synaptic cleft between the neurons.
91
What is synapses?
It is a process of transmitting signals from one neuron to the next.
92
What type of transport do hormones use?
They travel via blood.
93
What is insulin and glucagon?
Insulin and glucagon are hormones that take part in blood glucose regulation.
94
What is insulin used for?
Insulin is secreted by the pancreas to lower blood glucose levels by converting glucose into glycogen.
95
What is glucagon used for?
Glucagon is secreted by the pancreas to increase blood glucose levels by converting glycogen into glucose.
96
How does diabetes result from hormonal imbalance?
Diabetes is a disease which results from inability of the organism to properly regulate blood sugar levels. Imbalance in secretion of glucagon or insulin may result in diabetes.
97
Describe the action of thyroid stimulating hormone and thyroxine in metabolism.
Thyroid stimulating hormone stimulate the thyroid gland to release thyroxine which travels through out the organism increasing the metabolism of cells.
98
What is a role of ADH?
ADH is a hormone that increases the permiability of the collecting duct wall allowing for greater water re-absorption.
99
If ADH is used, what happens to the blood pressure?
It increases (water hoes effect)
100
What is the fight or flight response?
It is a hormonal response that is produces adrenaline in the adrenal glands. It increases the heart beat and the cell metabolism.
101
What regulates CO(2) levels in the organism?
The respiratory centre in the brain. Inter coastal muscles and the diafram are used.
102
What is a reflex?
A reflex response is when a signal travels to the spine rather then to the brain.
103
How long did life exist for according to the most recent evidence?
3.5 billion years.
104
How were the membranes formed?
Membranes may have formed spontaneously and the first simple cells may have used RNA as genetic information. Ribozymes may have played a role in this development .
105
What are ribosymes and what were their alleged function?
Ribosymes were RNA like enzymes which can catalyse reaction under certain circumstances.
106
What cells existed first? What evidence are there?
Prokaryotic. There are fossil evidence.
107
What is endosymbiosis?
Endosymbiosis is a theory that prokaryotic cells have combined in order to survive. This explains why mitochondria and chloroplast have multiple membrane.
108
How does sequencing of common proteins can be used to provide evidence for evolution?
Common proteins can be sequenced and compared between species. IF the sequences are similar then a relationship can be formed.
109
How DNA-DNA hybridisation can be used to provide evidence of evolution?
2 DNA strands are separated an trying to be joined together. The joining of the bases can be used to establish a relationship.
110
How DNA sequencing can be used to provide evidence of evolution?
Basically sequence bases and compare them. Very nice.
111
What are phylogenetic trees used for?
Phylogenetic trees are used to represent evolutionary relationships.
112
How do mutations can be used to determine the evolutionary relationships?
Mutations accumulate over time and the rate of mutation is relativley constant over time. This enables it to be used as 'clock'.
113
How can we determine the species?
A species that reproduces sexually can be defined by the ability of its members to actually or potentially interbreed to produce fertile offspring.
114
What other methods could be used to determine the species? Name 3.
1. Morphological similarity.
2. Biochemical similarity.
3. Sharing a common gene pool.
115
What is the function of reproductive isolating mechanisms?
Reproductive isolating mechanisms act to maintain distinct species.
116
What pre-zygotic organisms are there?
1. Temporal (seasonal) isolation
2. Behavioural isolation
3. Mechanical isolation
4. Gamete isolation
117
What post-zygotic organisms are there?
1. Hybrid inviability.
| 2. Hybrid sterility.
118
What is the ultimate source of genetic variation?
Mutations are a permanent change in the sequence of DNA nucleotides and is the ultimate source of genetic variation.
119
What are additional sources of genetic variation in sexually reproducing alley?
Crossing over, random assortment and fertilisation.
120
What is a gene pool?
A gene poolcomprises all the genetic information in an interbreeding population.
121
What does large gene pool indicates?
Large gene pool indicates considerable genetic diversity and is found in populations that are more likely to survive selection pressures.
122
What are selection pressures?
An agent of differential mortality or fertility that tends to make a population change genetically.
123
What is natural selection?
Natural selection is a process in which organisms that are better adapted to their environment are more likely to survive and produce offspring.
124
What are the results of natural selection?
Natural selection results in a change of the frequency of alleles in the population.
125
What is genetic drift?
Genetic drift is a process by which the frequency of alleles is changed due to events not relating to traits of the individuals.
126
Describe the process of allopatric speciation?
If 2 groups can no longer interbreed due to geographic isolation then over time, there are different selection pressures in the two groups. Different traits are selected for in the two groups and over time they become more genetically different. Eventually the two groups can no longer interbreed thus produce fertile offspring even if brought back together.
127
How does convergent evolution occur?
Similar selection pressures in different environment may lead to convergent evolution.
128
How does divergent evolution occur?
When new niches become available to a species, for example as a result of succession or following an environmental change, different selection pressure may lead to divergent evolution or adaptive radiation.
129
What is primary succession?
It's a process where initialy, lower life forms (pioneers) are able to colonise the rock. These alter the environment to make more suitable for other species to colonise. This allows for the development of soil and large plants and eventually insects and animals. Eventually, a mature community is formed.
130
What happens to the species with low genetic diversity?
Species or population that have a reduced genetic diversity have a higher risk of extinction.
131
Draw a neuron.
https://scx1.b-cdn.net/csz/news/800/2018/2-whyareneuron.jpg
