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Year 1 Biology > Genetic information, variation and relationships between organisms > Flashcards

Genetic information, variation and relationships between organisms Flashcards

1
Q

What is Biodiversity?

A

Variety in an ecosystem

Variety of habitats and a variety of species

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2
Q

What is Species Diversity?

A

number of different species

number of individuals for each species

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3
Q

What is Genetic Diversity?

A

variety of alleles in a species population

the larger number of individuals in a species, the larger the genetic diversity

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4
Q

The benefit of high species diversity

A

Stable ecosystem

each species is less likely to become extinct (due to high genetic diversity)

& if a species does become extinct it will not affect the food chain as there are other species available

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5
Q

How to measure Species Diversity for an area?

A

Species Diversity Index

takes into account the number of different species and how many individuals there are for each species

the larger the species diversity index, the larger the species diversity

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6
Q

How does deforestation lower species diversity?

A

(deforestation is the removal of trees for wood & space)

decreases plant species diversity

less variety of habitats

less variety of food sources

decreases animal species diversity

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7
Q

How does agriculture/farming lower species diversity?

A

deforestation to make space for farm

only grow a few plants & keep a few animal species

selectively breed plants & animals

use pesticides to kill other species

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8
Q

What is Classification?

A

placing organisms into groups

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9
Q

What is Hierarchical Classification?

A

large groups divided into smaller groups with no overlap

domain, kingdom, phylum, class, order, family, genus, species

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10
Q

What is Binomial Naming System?

A

using Genus name and Species name to name organism

Genus name first in capital, Species name second in lower case

e.g. tiger = Felix tigris

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11
Q

What is a Species?

A

a group of individuals with similar characteristics that can interbreed to produce fertile offspring

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12
Q

Why are the offspring from 2 different species mating infertile?

A

offspring will have a odd number of chromosomes

therefore, cannot perform meiosis, cannot produce gametes

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13
Q

What is Phylogenetic Classification?

A

based on evolutionary relationships – how closely related different species are and how recent a common ancestor they have

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14
Q

What is Variation?

A

difference in characteristics between organisms

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15
Q

Types of Variation

A

intraspecific = differences between organisms of the same species

interspecific = differences between organisms of different species

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16
Q

Causes of Intraspecific Variation

A

Genetic Factors = same genes but different alleles (allele are different type/forms of genes)

Environmental Factors

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17
Q

Causes of Interspecific Variation

A

Genetic Factors = different genes and different alleles

Environmental Factors

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18
Q

Properties of Discontinuous Characteristics

A

characteristics fall into certain groups with no overlap (e.g. blood group) – determined by genetics only (a single gene)

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19
Q

Properties of Continuous Characteristics

A

characteristics show a range (e.g. height) – determined by genetics (a few genes, polygenes) and environment

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20
Q

What is Genetic Diversity?

A

genetic variation, the variety of alleles within a population of a species

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21
Q

Benefit of high genetic diversity

A

species able to adapt with changes in the environment
e.g. if a new disease arises, some individuals will have characteristics to survive, and will reproduce passing on their alleles, so the species does not become extinct

22
Q

What can lower genetic diversity?

A

small population size (e.g. founder effect – where the numbers start low, or genetic bottleneck – where the numbers decrease)

23
Q

What is natural selection and adaptation?

A

variation in population of species

(genetic diversity/genetic variation/variety in gene pool)

new alleles arise by random mutation

environment applies a selection pressure on the population

those with favourable characteristics/favourable alleles/selection advantage/better adapted survive, the others die [natural selection]

the ones that survive will reproduce, passing on their favourable alleles

if this happens for many generations, then that characteristic will become most common – the allele will become more frequent [adaptation]

24
Q

What are the 2 types of selection?

A

stabilising and directional

25
Q

What is stabilising selection?

A

when the environment favours those with the most common characteristic – those on the extreme dies out

the common characteristic increases in proportion

the range (standard deviation) will reduce

26
Q

What is directional selection?

A

when the environment favours those individuals with characteristics on one of the extremes

over time this will become the most common characteristic

normal distribution will shift to that extreme

27
Q

What is a Gene?

A

a section of DNA that codes for a protein

made out of intron and exon

intron = non-coding DNA (function e.g. turns gene on or off)

exon = coding DNA (codes for protein)

28
Q

How does a Gene/Exon code for a Protein?

A

made out of a sequence of bases

each 3 bases code for 1 amino acid (called triplet code)

therefore,

sequence of bases

determines sequence of triplet codes

which determine the sequence of AAs

= polypeptide chain/primary structure (folds to secondary, then to tertiary/quaternary)

29
Q

Properties of triplet code?

A

degenerate = each AA has more than one triplet code

non-overlapping = each base is read only once

stop codes = occur at end of sequence – do not code for an AA

30
Q

How does a mutation lead to a non-functional enzyme?

A

change in base sequence

change in sequence of triplet codes

change in sequence of AAs

change in primary structure

change in hydrogen/ionic/disulfide bonds

change in tertiary structure (3D shape)

change in active site shape

substrate no longer complementary

can no longer form enzyme-substrate complex

31
Q

How is a protein assembled?

A

by transcription and translation

transcription = production of a single-stranded complementary copy of a gene (called mRNA)

translation = use sequence of codons on mRNA to assemble protein (tRNA brings in AAs)

32
Q

What is mRNA?

A

messenger RNA

single stranded complementary copy of a gene

carries the code for assembling protein (on DNA called triplet code, on mRNA called codon)

33
Q

What is tRNA?

A

transfer RNA

single stranded RNA folded over into a ‘clover leaf’ shape (held by hydrogen bonds between the bases)

has an AA attachment site on the top

has 3 specific bases on the bottom (anticodon)

anticodon binds to complementary codons on mRNA

34
Q

DNA vs RNA?

A

deoxyribose sugar vs ribose sugar

thymine vs uracil

double stranded vs single stranded

one type vs two types (mRNA and tRNA)

35
Q

What is transcription?

A

occurs in nucleolus of nucleus

producing a single stranded complementary copy of a gene (called mRNA)

DNA is double stranded, 1 strand called coding strand & 1 strand called template strand, the template strand will be used to build mRNA

process,

DNA Helicase breaks the hydrogen bonds between complementary bases in the gene

the double strand of the gene unwinds

leaves 2 separate strands (1 coding strand and 1 template strand)

complementary RNA nucleotides bind to exposed bases on the template strand

RNA Polymerase joins the sugar-phosphate backbone of the RNA strand

leaves pre-mRNA (contains introns and exons)

the copies of the introns are removed by splicing

leaves mRNA

36
Q

What is Translation?

A

takes place on ribosomes of Rough Endoplasmic Reticulum

uses the sequence of codons on the mRNA to assemble the protein (tRNA brings in AAs)

process,

mRNA leaves nucleus via nuclear pore

mRNA attaches to a ribosome

complementary tRNA carrying specific AAs bind to the codons on mRNA via their anticodon

the AAs on the tRNA are joined by peptide bonds

37
Q

What does Meiosis produce?

A

4 genetically different cells, haploid (half the amount of chromosome/DNA)

38
Q

Benefits of Meiosis?

A

produces gametes which will be used in sexual reproduction in animals & plants

(2 gametes fuse to form a zygote, zygote develops into organisms)

39
Q

Stages of Meiosis?

A

Interphase/Meiosis I/Meiosis II/Cytokinesis

40
Q

Interphase?

A

G1: protein synthesis

S: DNA replication (doubles set of DNA)

G2: organelle synthesis

41
Q

Meiosis I?

A

Prophase I: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form, crossing over occurs

Metaphase I: homologous pair of chromosomes line up in middle of cell and attach to 	 		          spindle fibre via centromere

Anaphase I: spindle fibres pull, homologous pair of chromosomes separate to opposite sides 									          by independent assortment

Telophase I: chromosomes uncoil, nucleus reforms (left with 2 nuclei)
42
Q

Meiosis II?

A

Prophase II: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form

Metaphase II: chromosomes line up in middle of cell and attach to spindle fibre via 				  								centromere

 Anaphase II: spindle fibres pull, centromere splits, sister chromatids move to opposite sides 									          by independent assortment

Telophase II: chromatids uncoil, nucleus reforms (left with 4 genetically different nuclei)
43
Q

How does Meiosis produce Variation?

A

Crossing Over and Independent Assortment

44
Q

What is crossing over?

A

occurs in Prophase I of Meiosis I

homologous pairs of chromosomes wrap around each other and swap equivalent sections of chromatids – produces new combination of alleles

45
Q

What is independent assortment?

A

in Anaphase I of Meiosis I – the homologous pairs of chromosomes separate

- in Anaphase II of Meiosis II – the chromatids separate

- independent assortment produces a mix of alleles from paternal and maternal 	   	 	  chromosomes in gamete
46
Q

What happens to DNA mass in meiosis?

A

quarters

47
Q

What happens to Chromosome number in meiosis?

A

halves (haploid)

48
Q

What is Mutation?

A

Change in DNA

2 types: Chromosome Mutation and Gene Mutation

49
Q

What causes mutation?

A

random or due to mutagens (e.g. chemicals, radiation)

50
Q

What is a Chromosome Mutation?

A

In plants, inherit more than one diploid set of chromosomes – called polyploidy

In animals, homologous pair of chromosome do not separate in meiosis, so either inherit one extra or one less chromosome – called non-disjunction

51
Q

What is a Chromosome Mutation?

A

In plants, inherit more than one diploid set of chromosomes – called polyploidy

In animals, homologous pair of chromosome do not separate in meiosis, so either inherit one extra or one less chromosome – called non-disjunction

52
Q

What is a Gene Mutation?

A

a change in the base sequence of DNA

2 types = substitution and insertion/deletion

substitution = replace one base for another, changes one triplet code

can be silent (new triplet code codes for same AA), mis-sense (codes for a different AA, so protein shape changes slightly), non-sense (codes for a stop codon, so polypeptide chain not produced)

insertion = adding a base, deletion = removing a base

both insertion/deletion causes frameshift, all the triplet codes after the mutation changes, so normal polypeptide chain/protein not produced

Year 1 Biology (15 decks)

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