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Sociology :) > Bio 12 Semester 2 > Flashcards

Bio 12 Semester 2 Flashcards

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1
Q

Define DNA

A

DNA is the common genetic material for all organisms
and carries the information coded in genes

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2
Q

Account for the different location of DNA including; nuclear, plasmid, mitochondrial and
chloroplast

A

Nucleic Acids in prokaryotes (no nucleus, floating DNa )

DNA is found as a circular molecule in the cytoplasm as:
- Chromosomal DNA
– Plasmid DNA

Nucleic Acids in eukaryotes
Deoxyribonucleic acid (DNA) consists of two chains wrapped around each other in a spiral to form a double helix.
DNA is found in:
– Chromosomes in the nucleus of eukaryotes and cytoplasm of prokaryotes
– As circular DNA in mitochondria and chloroplasts

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3
Q

Describe the structure of DNA.
What is it made up of?

A

Elements: C, H, O, N P

Subunit: Nucleotides

Polymer (molecular building blocks):
-Nucleic acid
-DNA (deoxyribonucleic acid)
-RNA (ribonucleic acid)

Nucleic acids are involved with the
transmission of inherited information

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4
Q

Define DNA replication
Describe the process of DNA replication.
Where does it occur

Is it semi conservative (what does that mean)

A

-the process by which the genome’s DNA is copied in cells.
-occurs in the nucleus

-semi conservative
which means each new dna molecule contains one of the parent strands

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5
Q

Nucleotides

What is a nucleotide?

How many components do they have and what are they called?

What way does it grow in?

A

-the basic unit of a nucleic acid

-a nucleotide has three components

-Phosphate group

-5 carbon sugar (ribose in RNA and Deoxyribose in DNA)

-Nitrogen base (5 possible types )

Nucleotide bases are
(adenine and guanine)=purines
(thymine and cytosine)=pyrimidines

u=uracil

-carbons of sugar are linked from 1’ to 5’

-nitrogen base attached to 1’ and phosphate attached to 5’

-nucleotides are linked 5’ to 3’ and DNA strands grow 5’ (phosphate) to 3’ (hydroxyl)

-read from 5’ to 3’

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6
Q

DNA structure

A

-Each strand of DNA (2) is connected by hydrogen bonds
-Guanine bases always pair with
cytosine – via 3 hydrogen bonds
- Thymine bases always pair with
adenine – via 2 hydrogen bonds
* The two strands of DNA are
antiparallel

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7
Q

Nucleic Acids:

What is Ribonucleic acid (RNA)

What is its role

What are the three types

A
  • consists of a single chain.
    It plays a role in converting the genetic code of DNA into proteins.

– Transfer RNA (tRNA)
– Messenger RNA (mRNA)
– Ribosomal RNA (rRNA)

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8
Q

Account for the different location of DNA including; nuclear, plasmid, mitochondrial and
chloroplast.

A

DNA is found as a circular molecule in the

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9
Q

Enzymes involved in DNA replication
Explain what each does including:

1)Helicase
2)RNA Polymerase (primase)
3)DNA polymerase
4) DNA ligase

A

1)Helicase
-catalyses the unwinding of the parent DNA molecule, which results in both of the strands exposed to be used as the template

2)RNA Polymerase (primase)
-builds a short RNA primer sequence

3)DNA polymerase
-after primer
-extends primer by adding nucleotides to the growing 5’ to 3’ sequence
-leading strand is built normally
-lagging strand is built backwards in shorter okazaki fragments
-okazaki fragments are joined together with DNA LIGASE

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10
Q

Define biotechnology

What is and give examples of BIOtechnology

A

exploitation of biological processes for industrial and other purposes, especially the genetic manipulation of microorganisms for the production of antibiotics, hormones, etc.

The use of enzymes including endonucleases (restriction enzymes), ligases and
polymerases
* Amplification of DNA using the polymerase chain reaction
* The use of gel electrophoresis in sorting DNA fragments, including interpretation of gel
runs
* The use of recombinant plasmids as vectors to transform bacterial cells

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11
Q

Describe the processes of PCR, restriction enzyme digests and gel electrophoresis.

Describe the benefits and limits of PCR, restriction enzyme digests and gel electrophoresis.

A
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12
Q

Describe the processes of PCR, restriction enzyme digests and gel electrophoresis.

Describe the benefits and limits of PCR, restriction enzyme digests and gel electrophoresis.

A
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13
Q

Where does DNA replication occur

What does it produce?

A

-nucleus

-copy of a chromosome before a cell divides

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14
Q

What way does DNA polymerase build new DNA strands

Why?

What strand is built continuosuly

A

5’ to 3’

(sugar phosphate backbone, one is upside down compared to the other )

(5’ to 3’= phospoate connected to the molecules 5th carbon and ending at the 3rd carbon which is connected to base)

(5’ has phosphate at start of chain)

(phosphate to hydroxyl end)

only the leading strand is built continuously

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15
Q

How is rna different to dna

A

-rna is single stranded
-rna has a different sugar ribose
-base is uracile (what binds to adenine)

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16
Q

The Lagging Strand

A

-dna can only copy dna in a 5’ to 3’ direction, and the lagging strand is built 3’ to 5’

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17
Q

What is the cell cycle?

A

-derivation of all cells from pre existing cells through the completion of the cell cycle
-every cell coming from sperm and egg cell

The rapid procession of prokaryotic cells through their cell cycle by binary fission

The key events in the phases (G1, S, G2, M and C) of the eukaryotic cell cycle, including the characteristics of the sub- phases of mitosis (prophase, metaphase, anaphase and telophase) and cytokinesis in plant and animal cells

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18
Q

Chromosomes

What are they?

What are the three types of chromosomes?

A

DNA strands coil and twist into compact chromosomes

More chromosomes in a speciies does not mean more complexity

Reason for more chromosomes date back to evolution

1) Sex Chromosomes
-x and y chromosomes
-determine biological gender
-XX=female
-XY=male

-females can live without an x chromosomes and because only relevant to male reproductive traits
-Y chromosomes getting smaller, less usage

2)Autosomes
-not a sex chromosome
-same for all members of a species
-come in pairs that are called:
3) Homologous Chromosomes
-chromosome pairs contain the same genes but may have different versions of the gene

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19
Q

What is a Somatic Cell

What is a Sex Cell (Gametes )

A

Somatic Cells:
-Body cells
-All body parts have different ways of reading genetic code but have the same DNA
-Chromosome pairs

Gametes:
-sperm and egg cells create a new child
-has 50 % of required DNA

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20
Q

Describe the Process of Mitosis

What are the stages of Mitosis

A

Interphase (not a part of mitosis or meoisis)
-prophase
-metaphase
-anaphase
-telophase
-cytokenesis

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21
Q

Meosis: Crossing over and recombination

A

During Prophase I in meiosis,
chromosomes undergo a process called
crossing over and recombination
* This involves homologous chromosome
pairs sitting side by side, and one or more
arms of the chromosomes will twist
together.

At the chiasma, the arms of the
chromosomes will break and re-join on the
other homologous chromosome.
* This creates variation without disrupting
the genes that are present on that
chromosome.

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22
Q

Meosis

What is a haploid?

A

Sexual Reproduction in Eukaryotes

Egg (n) +Sperm (n) =zygote (2n)

Haploid=pne of each chromosome

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23
Q

What are the sources of variation in meosis (sexual reproduction)

A

1) Random Independent Assortment during metaphase 1. The combination of homogolous pairs moving to seperate poles of the cell may vary

2)Crossing over a recombination between the chromatids of homogolous chromosomes. The chromatids corssing over may contain different versions of the same genes, therefore recombination creates new combinations (what pairs cross over)

3) Fertilisation: Which gamete is fertilised (which sperm/egg cell was used)

4)Mutation

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24
Q

Meiosis errors

A

-individuals can have more or less chromosomes as a result of non disjunction of chromosomes in one of their parents

-non dijunction occurs when the chromosomes do not seperate properly in anaphase 1 or 2

-Triploid organisms are generally unable to undergo meiosis due to problems with chromosome pairing.

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25
Q

The results of meoisis

A

-in males, one cycle of meiosis results in 4 haploid gametes (sperm)

-in females it results in 1 haploid gamete and (ovum/egg) and 3 haploid polar bodies

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26
Q

Define the term gene

A

A gene is a segment of DNA that
codes for a protein

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27
Q

DNA is read as three-letter codes
called?

A

triplets

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28
Q

What do genes code for?

What are genes transcribed into? which is translated into what?

A

-proteins

-transcribed into RNA, which is then translated into the amino acid sequences that make up proteins

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29
Q

Explain Mendel’s principals of inheritance, Law of segregation and independent assortment.

What was the law of segregation?

A

-combined pure breead green and yellow pea plant, and got only yellow seeds, therefore yellow was deamed dominant

-yellow seeded hybrid plants breeded, but green was still produced, meaning the trait was hidden and recessive

Genotype
YY=homozygous
Yy=heterozygous

Phenotype=result of genotype

Law of segregation: During the formation of gamete, each gene separates from each other so that each gamete carries only one allele for each gene

Independent assortment:
the alleles of two (or more) different genes get sorted into gametes independently of one another.

30
Q

Alleles

What are they?

A

-represent different versions of a gene

-different version of a gene

-People inherit one allele for each autosomal gene from each parent, and we tend to lump the alleles into categories.

31
Q

Define heterozygous.

Define homozygous.

A

-homo= type copies of the same allele from each parents
AA or aa

-heterozygous
two different alleles for a trait
Aa

32
Q

Define genotype:

Define phenotype:

A

Genotype
-the genetic makeup of an organism, describes the genes
-combination of alleles present in an organism
-eg AA
Phenotype
-physical appearance
-observable traits; the expression of genotype
-eg; blue eyes, right or left handed

-genotype determines the phenotype of an individual

33
Q

What are the two genetic cross types ?

What are test crosses used for?

How to do a monohybird cross

A

-monohybird
-dihybrid

used for:
-used in plants and insects and determine inheritance

a monohybird cross
-assign genotype
-punnet square
-genotype and phenotype percentages

34
Q

Types of Inheritance:

Sex Linked:

Autosomal:

A

-Sex linked traits
-on the X chromosome
-male is XY and female is XX, meaning female has back up X chromosome
-example; gene for colour blinness is on x chromosome

Sex Linked= X^A X ^a

Autosomal:
-2 or more genes being on the same autosomes (not sex chromosomes)

A,a

Complete dominance:
-heterozygote shows the dominant trait

Codominance/co recessive if only recessive allele
-Both traits shown because both alleles are dominant A^B A^
-hetorozygote shows both traits

Example= F^R F^R x F^B F^B = F^R x F^B
Red and Blue Plant is created

Incomplete Dominance
-Heterozygote shows a mix of both traits (can be more or one)
A^B x A^M = purple plant

35
Q

Lethal Alleles:

A

-lethal if individual is homozygous

-allele can be dominant or recessive

36
Q

Difference between coding and non coding DNA

A

Noncoding DNA does not provide instructions for making proteins

Coding=encodes for a protein

37
Q

What are polygenetic traits

A

-a trait whose phenotype is influenced by more than one gene

-a characteristic, such as height or skin color, that is influenced by two or more genes

38
Q

Transcription

A

-making a copy
-DNA replication= copy of whole DNA, transcription is using the proteins
-transcription=make a copy of gene so that it can be taken out of the nucleus
-only template strand is used
-built 5’ to 3’

39
Q

Post Transcription Modification

What are introns?

A

In eukaryotes, transcription produces pre-mRNA molecules. These molecules are then modified to form (mature) mRNA via:

Splicing (removal of introns)
Addition of 5’ cap
Addition of 3’ poly-A tail
Prokaryotes do not undergo post-transcriptional modification.

Introns sequences of DNA that have no protein-coding function.
Introns are removed and exons rejoined by RNA splicing before the mRNA leaves the nucleus

40
Q

What are ribosomes?

What are tRNA molecules

A

-ribosomes
-Made of subunits of protein and ribosomal RNA (rRNA).
-rRNA makes ribosomes
-large and small subunits

Trna molecules
There is a specific complimentary tRNA molecule and anticodon for each type of codon.

The anticodon is the site of the 3-base sequence that ‘recognizes’ and matches up with the codon on the mRNA molecule.

-amino acid attachment site
-anti codon
-ribosome attachment point

41
Q

Translation

A

-occurs in rybosome in cells cytoplasm

-the process of building a protein from amino acids, guided by the sequence of codons om the mRNA

42
Q

Structures involved in translation

A

messenger Rna molecules
-carries code from the DNA so that it can be translated into an amino acid sequence

Amino Acids
-constructs hte polypeptides (proteins)

Ribosomes
-provide the environment for tRNA attachment and amino acid linkage

43
Q

The Genetic Code

A

-DNA codes for the assembly of amino acids and polypeptides

The code is read in a sequence of bases called:
-triplets on DNA
-codons on mRna

Each codon codes for an amino acid
More than one codon can code for the same amino acid, making it degenerate

Some codons construct the tart and stop sequences for the polypeptide chain formation

44
Q

Name the 3 nucleic acids

A

-transfer tRNA

-messenger mRNA

-ribosomal rRNA

45
Q

Define genetic variation

A

Genetic variation is the difference in DNA among individuals or the differences between populations among the same species.

46
Q

Define mutation

A

-permanent changes in the DNA nucleotide base sequence of an organism which may result in the formation of new alleles.

-The effects of mutations vary depending on their location both within chromosomes and the body of the organism.

47
Q

Identify the factors that cause mutation

Is it random or spontaneuos?

Examples of mutagens

A

-may occur randomly or spontaneously

-arise from errors in replication

-may be induced by environmental factors (mutagens)

Including:
radiation (e.g. UV rays)
viruses
microorganisms
environmental poisons and irritants
alcohol and diet

48
Q

Types of mutations

What are points mutations- substitution mutations

A

Point mutations: Substitution mutations:

The change of a nucleotide

Silent Mutations:
-occurs when the substitution results in a new codon that still codes for the same amino acid

Nonsense mutations:
-occurs when substitution results in a premature stop being introduced and shortening polypeptide chain

49
Q

Frame shift mutations

(insertions or deletions )

A

Single or multiple bases are inserted or deleted.
Causes a ‘frame shift’ - results in new amino acids in the polypeptide chain from the point of insertion/deletion onwards.
Resulting protein is significantly different from original (most likely non-functional).

50
Q

What are chromosomal mutations

A

the mutation of the chromosomal segments of the DNA strands

changes in the number or structure of chromosomes.

51
Q

Fitness of mutation

What does this refer to?

A mutation can be…

A
  • its value to the survival and reproductive success of the organism.

-Lethal: Embryos are non-viable.
Harmful: e.g. Down syndrome, sickle cell disease. Lower an individual’s fitness.

Silent (neutral): No noticeable effect on the phenotype.

Beneficial: Occasionally mutations may be useful, particularly in a new environment, e.g. insecticide resistance in insects, antibiotic resistance in bacteria.

52
Q

Mutations to variation

What cells can mutation be in?

A

All new alleles arise through mutation

New alleles introduce genetic variation

Natural selection and evolution act on variation

Most mutations occur in somatic cells and are not inherited.

Only mutations in gametes can be inherited.

53
Q

Why is diversity important?

A

-more likely for species to survival
-inbred species are less likely to survive if the environment changes

54
Q

What is a species?

What is a population?

A

species
-grouping of organisms that can interbreed and produce viable and fertile offspring in the natural environment

What is a population?
comprises the total number of one species in a particular area.

55
Q

What is a gene pool?

A

-the complete set of alleles carried in a population

-individuals in the population will have some but not all of the available alleles

-large gene pool indicates more diversity

The range of variation possible in a population is restricted by the alleles available in the gene pool

56
Q

What is a fixed allele?

A

-Genes with only one allele in the gene pool are said to be fixed.

57
Q

Environmental selection pressures

A

-Phenotypes may be selected for and give the organism a ‘selective advantage’. Such organisms have a higher ‘fitness value’.

Phenotypes may be selected against. Such organisms have a lower ‘fitness value’.

Selection factors can be natural or artificial.

58
Q

Steps involved in natural selection:
Reciple for natural selection

A

-variation of phenotypes exist in populations
-factors in the environment act as cselection pressures on phenotypes

Differential reproduction occur:
-phenotypes are selected for and against, these individuals survive and reproduce in larger numbers, their allele frequency becomes higher

-phenotypes selected against, do this in lower numbers, reducing frequency of alleles

59
Q

Selection Pressures

Give examples

A

Competition between species for food or territory
Predator-prey relationships
Competition within species for food or water
Competition within species for territory/space
Sexual selection
Climatic conditions

60
Q

Natural selection

A

-is a mechanism for evolution

Natural selection increases the frequency of ‘favorable alleles’ in the gene pool, but it does not produce the “perfect organism”.

Natural selection does not create new alleles or new phenotypes, it can only work on existing phenotypes.

Natural selection reduces variation in populations.

Natural selection depends on the environment, changes in the environment can alter selective pressures.

61
Q

Artificial selection

A

Humans have controlled the breeding of domesticated animals and plants for centuries.
Artificial selection or selective breeding, involves breeding (selecting) individuals with the most desirable phenotypes. It can result in an astounding range of phenotypic variation over relatively short time periods.
Selection imposed by humans is often more rapid and intense than that occurring in nature.

62
Q

Steps to artifical breeding

A

Determine the desired trait
Interbreed parents who show the desired trait

Select the offspring with the best form of the trait and interbreed these offspring

Continue this process until the population reliably reproduces the desired trait

63
Q

Issues with artifical breeding

A

-reduces resistance to change

-reduces biodiversity

-generates genetic abnormalities

64
Q

Allele frequencies

A

-How common particular alleles of a gene are in the population.

65
Q

Evolving populations

What are factors resulting in changes in gene frequencies

A

-mutation

-gene flow: migration of individuals and their genes between populations
-(immigration and emigration).
-makes different populations gene pools similar

-genetic drift: changes in allle frequencies due to random large scale events
Greatest effect is when allelic frequency is very low or the population is very small
can be seen in random mating, fertilisation chance, the bottleneck effect and the founder effect.

-environmental selection pressures: natural selection working against particular phenotypes

-non random mating: individuals seek our specific phenotypes with which to mate

66
Q

Population size and genetic diversity

A

-smaller populations have fewer alleles to begin with, change of alleles is faster

-small populations have a greater risk of inbreeding

-populations with low diversity are of risk of dangers from environmental pressures

-endangered species and captive breeding populations are at risk of this

67
Q

Genetic Drift: Population Bottlenecks

A

Events, such as fires, floods, disease, etc…, may severely reduce the size of a population.

By chance, the small sample that survives will often not be representative of the original, larger gene pool.
Allele frequencies will change by chance and the genetic diversity may decrease.

68
Q

Genetic Drift: The founder Effect

A

-small number of individuals migrate away from their population

-This founder population will have a small and probably non-representative sample of alleles from the original gene pool.
The founder population may evolve in a different direction than the parent population.

69
Q

Speciation

What is it?

What is Allopatric speciation:

What are the steps

A

-the process by which new species are formed

Allopatric speciation:
-populations become isolated and differences accumulate overtime

1)moving into new environments
-this population still has a common gene pool

2)geographical isolation
-physical barriers isolate the 2
-gene flow is prevented

3)formation of a subspecies
-environmental pressures from each environemtn occur, selection pressures, species form different traits

4) reproductive isolation

Subspecies become reproductively
isolated and attain species status.
Even if geographical barriers
are removed interbreeding will not occur.

70
Q

Isolationg mechanisms

A

-Geographical isolation
Occupation in different niches within the same ecosystem
Temporal (time) isolation
Behavioural isolation
Structural or morphological isolation
Hybrid inviability

Sociology :) (7 decks)

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