A3. 1 Unity and diversity

Question 1

how can we classify organisms? (strictly hierarchial)

F.H.M.D.R.A

Answer 1

1. by feeding habits (carnivore/herbivore)
2. by habitat (land/aquatic)
3. by movement
4. by daily activity (nocturnal/diurnal)
5. by risk (harmless/venomous)
6. by anatomy (plant/animal /vertebrate/ inter-vertebrate)

Question 2

how to we categorise organisms

Answer 2

initially by morphology
- the appearance of the organism
- whether it is a single cell
- nucleus or non nucleus
- if it has a nucleus, is it unicellular or multicellular?

Question 3

what is each category in which organisms are catergorised called?

Answer 3

a taxon (plural taxa)
- largest taxon is a domain –> it contains more specific taxa such as kingdom and species

Question 4

what is taxonomy?

Answer 4

the classification of a species based on their shared traits and lineage

Question 5

continuous vs discontinuous stateof variations?

Answer 5

discontinuous is when variation can be placed into distinct categories (Type A blood vs type b)

continuous is when a variation has a wide range of possibilities (how a tall tree can grow

Question 6

what is morphological classification?

Answer 6

the classification system of carolus linnaeus to group species as groups of organisms. This system is based on their names, and the physical features of the organisms

Question 7

what is Binomial nomenclature?

Answer 7

the system of naming organisms using two names. E.g myrmecophaga tridactyla, meaning eater of ants + three fingers.

• first part of the name is the genus, while the second part is the species
• species in the same genus have similar traits
• the genus name has a capital letter while the species lowercase, both written in italics when typed, or underlined when written by hand

Question 8

what are the main objectives and associated rules when using binomial nomenclature?

Answer 8

1. each organism has a unique name that cannot be confused with another organism
2. the names can be universally understood, no matter what nationality is using the name
3. there is some stability in the system, so that the people cant change the names of the organisms without valid reasons

Question 9

what is the controversial biological species concept? earnst mayr 1942

Answer 9

1. in order to be classified as the same species, the organism must be able to breed together
2. and produce fertile offspring

Question 10

what characteristics can be taken into account when deciding on what counts as a species?

Answer 10

1. the ecological niche of an organism

• because microbes are single-celled, its challenging to only use morphology to determine the species
• where they live and how they eat are part of classifying microbes into different species

2. genetics
3. the types of molecules an organism can produce
4. for extinct species, their lineage
   - if we find a fossil of an extinct snail that has a shell similar to a modern species, we can use the similarities to assign it a species name based on its position on the same part of the evolutionary tree as the existing species.

Question 11

what is speciation?

Answer 11

the process by which a population is separated into two groups that can no longer reproduce together. because these two species can no longer interbreed and produce offspring, they aren’t considered as the same species

• one part of the population evolves one way, and the other while producing different sets of mutation, evolves in a different way
• for example Galápagos finch. Different species of these birds live on different islands in the Galápagos archipelago, located in the Pacific Ocean off South America. The finches are isolated from one another by the ocean.

Question 12

what are diploid cells?

Answer 12

• nucleus which has chromosomes organised into homologous pairs (23 from the mother, 23 from the father)
• found in somatic cells (bone, muscle)
• represented by 2n in humans (2x23)
• formed by mitosis

Question 13

what are haploid cells?

Answer 13

• total number of chromosomes 23 in a cell
• found in gametes/ sex cells
• represented by n
• formed by miosis

Question 14

what is a karyogram and why is it used?

Answer 14

a representation of chromosomes of a cell, arranged according to standard format. Its used to show a person’s karyotype, which is the specific number and appearance of the chromosomes in their cells.

Question 15

how are chromosomes placed in a karyogram?

Answer 15

they’re placed according to their - - - -

• shape and
• size;

their shape mainly depends on the position of their centromere

Question 16

how is a karyogram image obtained?

Answer 16

1. the cells are stained and prepared under a glass slide to see their chromosomes under a light microscope
2. photomicrograph images of the chromosomes are obtained during the mitotic metaphase of cell division
3. the images are cut out and separated
4. the images of each pair of chromosomes are placed in order by size and position of their centromeres. And generally, they’re arranged by decreasing length, with exception to the 23rd chromosome, because it can contain one or two X chromosomes, which are larger than the 22nd pair.

Question 17

Explain the evolution of human chromosome 2 and its hypotheses

Answer 17

modern humans and other humans that no longer exist have 46 chromosomes, while our last common ancestor gorillas and chimpanzee have 48 chromosomes, which is two more than we do.

To explain what happened to our second chromosome number, two theories are formulated:

1. a complete chromosome disappeared
2. two chromosomes from an earlier common ancestor fused and became a single chromosome

a whole chromosome is very unlikely to disappear because removing hundreds of genes would cause a major threat to the viability of the species.
It’s important to note that chromosomes can be metacentric (centrosome in the center), and acrocentric (the centromere is at one end, making the arm of one chromosome much shorter)
On the other hand, the second hypothesis

That being said, the second hypothesis holds more evidence as it says chromosome 2 in humans is the result of the fusion of chromosomes 12 and 13 in a shared ancestor. both of them have a similar length to the human chromosome, with some parts overlapping.

The position of the human chromosome centromere lines up with chimp chromosome 12 but not with 13. However, because of satellite DNA of the human chromosome, (the type of DNA usually found in centromeres) it also corresponds with chimp chromosome 13 as well.

• In terms of banding patterns, the long arm of chimp chromosome 12 matches the short arm of human chromosome 2, and the long arm of chimp chromosome 13 matches that of the long arm of human chromosome 2.
• Additionally, the idea to support the fusion is also the presence of telomeric DNA in chromosome 2. Because telomeres are located in the tips of chromosomes, it is unusual to find telomeric repeating DNA in the centre of a chromosome. The presence of such in chromosome 2 suggests that chimp chromosomes 12 and 13 fused through their telomeres.

Question 18

what are alleles?

Answer 18

different or alternative versions of genes, inherited from each parent.

Question 19

what is a single nucleotide polymorphism (SNP) and why are they important?

Answer 19

it is a variation at a single position of a dna sequence. while some may have no negative effects on protein structure and function, some do which can lead to genetic diseases such as sickle cell

• if you switch many aminoacids, it might affect the protein therefore leading to error
  -is caused by error in mRna, error in translation.

Question 20

what is the human genome project?

Answer 20

in the 1990s an international cooperative venture called the Human genome project set out to sequence the complete human genome, together with all its bases in human DNA.

when they achieved this in 2013, they found that humans have 20,000-25,000 genes.

Question 21

using which databases can genetic information be explored in bioinformatics?

Answer 21

1. swiss prot- a database of protein sequences
2. ensembl- a database and browser of genomic information about humans and other vertebrates
3. Genbank - annotated collection of all publicly available DNA sequences

Question 22

explain mitochondrial DNA

Answer 22

• all eukaryotes have mitochondria which is present only in the egg and not in sperm cell.
• As it is passed down without alteration/integration to offspring, it doesn’t shuffle, unlike in chromosomal DNA,
• in this way, we can trace ancestral history, as it has evolutional significance

Question 23

what is genome sequencing?

Answer 23

the process of determining the entirety of s DNA sequence of an organism’s genome at a single time.

Question 23

explain personalised medicine?

Answer 23

information about a person’s genetic makeup that can be applied to an individual when prescribing treatments, through genetic sequencing

• identifying patterns with people who share a specific same genetic sequence to develop drugs hat might treat diseases such as cancer, type 2 diabetes or cardiovascular disease, as they require more treatments based on the disease’s stage.

Question 24

what are the processes of the production of new medicine through the genetic sequencing of the human genome?

Answer 24

• find beneficial molecules that are produced naturally in healthy people
• find out which gene controls the synthesis of the desired molecule
• ## copy the gene and use it to instruct synthesis of that molecule artificially
• distribute the beneficial therapeutic protein as a new medical treatment

Question 25

what is parthenogenesis

in insects

Answer 25

a reproductive strategy usuallyin vertebrate species (insects) that involves development of a female gamete without fertilisation, or without the need of a male gamete

Question 26

what is vegetative propagation

Answer 26

the asexual method of reproduction in plants through regeneration stems, roots and leaves., for example strawberries.

Question 27

Howdo bacteria reproduce asexually and how?

horizontal gene transfer, plasmid transfe

Answer 27

bacteria reproduce asexually by growing larger to make a copy of their genetic material, and then splitting into two identical daughter cells. Because they dont reproduce using breeding, no gametes are produced.

Question 28

what is a vertical gene transfer?

Answer 28

the transfer of genetic information from a parent to their offspring (mother to daughter cells)

Question 29

what is a horizontal gene transfer

(donor to recipient)

Answer 29

while other organisms usually receive genetic information once in their life, bacteria do it throughout. the two cells can attach to each other and exchange sequences of DNA during plasmid transfer.

Additionally, this gene transfer can be done even if the host bacterium is not of the same species.

Question 30

what is the tree of life concept?

Answer 30

the connection between the diversity of all life on Earth.

Question 31

what are xenologs/ jumping genes? Example?

Answer 31

a sequence of DNA that has more in common with another species than its own.

(they can travel in plasmids from one bacteria to another).

An example of this is yeast cells containing bacterial DNA.

Question 32

what is an interspecific hybrid and why can’t they produce offspring?

Answer 32

Interspecific hybrids are the crossing of two species, such as a horse and a donkey producing a mule. These hybrids are infertile, and cannot reproduce because of their atypical chromosomes make it difficult for pairs of chromosomes to match up during meiosis, therefore produce gametes.

Question 33

What is eDNA (environmental DNA)

Answer 33

eDNA is DNA that is released from an organism’s dead cells into the environment. It uses DNA barcoding (short sequence of DNA inside a cel), to identify the specific organism.

Question 34

what are bioindicators and indicator species?

Answer 34

living organisms whose presence in an environment indicate the health levels of the natural ecosystem of that environment.
For example, the presence of trout in a river indicating fresh water of the river.

Question 35

what is the rank of the different taxa groups (hierarchy of biological classification)

Answer 35

1. kingdom
2. phylum
3. class
4. order
5. family
6. genus
7. species

KPCOFGS

Question 36

describe the wholly mammoth concept and how DNA sequencing can help revive species?

Answer 36

insert edited DNA from an extinct species into the nucleus of a reproducing cell.

in this case, they want to revive the wholly mammoth to decrease carbon dioxide from releasing into the air, by collecting the genes of the mammoth and inserting its DNA into the nucleus of an asian elephant’s cell, since its most similar to the mamoths gene structure

Question 36

what are advantages and disadvantages of DNA sequencing

Answer 36

advantages
- allows to closely analyse genes for inspection of mutations therefore diseases
- a step forward to progressing in personalised medicine

disadvantages
- lack of autonomy
- certainty of results because of overly complex patters

Question 36

what are advantages and disadvantages of environmental DNA?

Answer 36

advantages
- used to configurate ecosystem
- used to learn about specific species

disadvantages
- sometimes migration of animals can cause misrepresentation, therefore inaccuracy of the analysis

Question 37

what is a plasmid?

Answer 37

A small extrachromosomal DNA molecule within the cell physically separated from chromosomal DNA that can replicate

they can be used to clone, replicate or manipulate genes