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HSC Biology (2022) > Module 5 > Flashcards

Module 5 Flashcards

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1
Q

Define mitosis

A

Cell division resulting in two identical daughter cells (diploid) with the same number and kind of chromosomes as the parent

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2
Q

Define meiosis

A

Cell division resulting in four daughter cells (haploid gametes) each with half the number of chromosomes as the parent cell

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3
Q

Explain the process of sexual reproduction in animals.

A
  • Gametes are produced by parent organisms.
  • The make gamete (sperm) fertilisers the female gamete (egg) either internally or externally.
  • Fusion of gametes results in the production of a zygote, containing the genetic information from both parents.
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4
Q

Explain the process of sexual reproduction in plants.

A
  • Flowers serve as the reproductive organ.
  • During pollination male gametes (pollen) enter the ovules via wind or insects.
  • Fertilisation occurs and ovules grow into fruit/seed.
  • Seeds are freed and grow into a new seedlings.
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5
Q

How to plants replicate asexually?

A

Stem or roots sprout to form new individual organisms without the need for seeds.

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6
Q

Advantages and disadvantages of internal fertilisation in animals.

A

Advantages:

  • increased likelihood of fertilisation as egg and sperm are close.
  • female reproductive organs provide ideal conditions for zygote.
  • protection from external environment

Disadvantages:

  • fewer offspring produced.
  • more difficult for partners to mate.
  • risk of STIs 😬
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7
Q

Advantages and disadvantages of external fertilisation in animals:

A

Advantages:

  • large number of gametes produced generally resulting in more offspring
  • simple, does not require mating rituals

Disadvantages:

  • species must produce a large number of gametes which requires lots of energy.
  • requires a aquatic or watery environment
  • zygote less protected from environmental conditions
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8
Q

Explain asexual reproduction in fungi.

A
  • Budding: the nucleus of the fungi cell divides and splits via cytokinesis, creating a new bud.
  • Spores: mitosis produces identical daughter cells which are distributed into the environment by wind.
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9
Q

Explain sexual reproduction in fungi.

A
  • meiosis: gametes are created which produce non-identical spores to be distributed into the environment.
  • Plasmogamy: two genetically unique fungi cells fuse, creating a hybrid.
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10
Q

Explain reproduction in bacteria.

A

Bacteria reproduces asexually via binary fission (mitosis):

  • dna replicates
  • a single cell splits via cytokinesis into two identical daughter cells
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11
Q

Explain the process of sexual reproduction in protists.

A
  • For haploid protists: two haploid cells fuse to form a zygote which then undergoes meiosis to from new haploid cells.
  • For diploid protists: cell undergoes meiosis to produce 4 gametes which are fertilised, forming new diploid cells.
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12
Q

Advantages and disadvantages of sexual reproduction.

A

Advantages:

  • Variation in the population, increasing resilience and resistance.
  • Species can adapt to their environment
  • Both heredity and infectious disease less likely to effect the entire population.

Disadvantages:

  • large time and energy commitment
  • Requires a mating partner (can lead to competition)
  • Fewer offspring produced less rapidly.
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13
Q

Advantages and disadvantages of asexual reproduction.

A

Advantages:

  • Rapid population of an environment
  • No requirement for mate
  • Able to occur under environmental pressure due to low energy commitment.
  • No need for investment of care of offspring.

Disadvantages:

  • Lack of genetic diversity
  • Susceptibility to disease may cause large scale extinction.
  • Less ability to adapt to external pressures.
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14
Q

Explain the process of fertilisation and implantation.

A
  • Ovulation: The female gametes (ovum) are released into the fallopian tubes.
  • Fertilisation: When the fusion of sperm and egg is successful.
  • Implantation: If fertilisation is successful the new zygote migrates into the uterus and embeds itself into the endometrium after 7 days.
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15
Q

Explain how oral contraceptives prevent pregnancy.

A

There are two main methods of oral contraception.

  • progesterone-only method: prevents ovulation but not reliably, as-well as thickening the mucous in the cervix, making it difficult for the sperm to migrate.
  • Combination method: the addition of oestrogen causes the body to cease release of eggs into fallopian tubes completely.
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16
Q

How is selective breeding used for specific outcomes.

A
  • Based on the understanding that phenotypes are hereditary so plants with desirable traits are pure or crossbreed over generations.
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17
Q

What are the benefits of artificial insemination in agriculture?

A
  • gives farmers the ability to synchronise pregnancy’s
  • can be used to pass on specific traits
  • increases probability of successful fertilisation
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18
Q

What are the benefits of artificial pollination in agriculture?

A
  • cross breeding of desirable traits
  • ensures successful pollination
  • does not rely on bees
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19
Q

How is genetic engineering used in agriculture?

A
  • Allows for the manipulation of the genetic material of plants to create ideal traits.
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20
Q

What is the interphase

A

Cell replication is prepared as DNA is replicated to produce two copies of each chromosome

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21
Q

What is the prophase?

A
  • duplicated chromosomes condense
  • the strands of of the miotic spindle held together by the centromere divide the cell.
  • the nuclear enveloppe breaks down
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22
Q

What is the metaphase?

A
  • chromosomes becomes fastened to the centromere at the equator of the cell
  • chromosomes line up along the equator
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23
Q

What is the anaphase?

A
  • centromeres divide so each chromatid has its own centromere
  • microtubles bind the to the chromatids, separating them from one and other.
  • there is now a copy of each chromosome
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24
Q

What is the telophase?

A
  • nuclear membranes from around each daughter cell

- the cell splits down the middle to form two identical daughter cells (cytokinesis)

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25
Q

What occurs during meiosis 2?

A

The chromatid pairs split into 4 single chromosomes creating 4 haploid cells.

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26
Q

Define haploid

A

Single set of unpaired chromosomes.

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27
Q

Define diploid

A

A cell containing two complete sets of chromosomes (one from each parent)

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28
Q

What is a genotype?

A

alleles present in an organisms chromosomes

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29
Q

What is a phenotype?

A

Outward appearance of an organism determined by alleles present
Influenced by:
Genotype
Interaction between genotype and the environment
Epigenetic factors

30
Q

Define allele

A

Alternative forms of a gene ( in Latin it means rival)

31
Q

Define gene

A

A section of DNA encoding a particular characteristic

32
Q

What is the Watson/Crick model of DNA?

A
  • Two helical strands twisted around each other in a double helix.
  • Strands are held together in a ladder structure by nucleotide bases bonded by hydrogen bonds.
33
Q

Define Heterozygous

A

Different alleles in a gene pair

Pp pP

34
Q

Define homologous

A

Identical alleles in a gene pair

pp PP

35
Q

What is autosomal inheritance?

A 
When traits (alleles) are based on the autosomes (all chromosomes except x & y)
In AI an offspring will inherit one set of chromosomes from each parent equally
36
Q

What is sex linkage inheritance?

A

When traits (alleles) are passed on the sex chromosomes (x or y) may either be x linked or y linked

37
Q

What are the nucleotide bases?

A 
A - adenine
G - guanine
C - cytosine 
T - thymine 
U - uracil (replaces adenine in RNA)
38
Q

List the five components of DNA

A

A DNA double-stranded helix consists of a sugar phosphate backbone and four nitrogenous bases-Adenine, guanine, cytosine and thymine. The backbone is connected by covalent bonds and the bases are connected by hydrogen bonds.

39
Q

What are the three types of RNA?

A

Messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA ( rRNA, the site of protein synthesis).

40
Q

Explain the role of the enzyme helicase in polypeptide synthesis.

A

Helicase is an enzyme that unwinds the DNA double helix by breaking the hydrogen bonds that connect the nitrogen bases.

41
Q

What is the complementary base pair to adenine?

A

Adenine is a purine base that pairs with Thymine, a pyrimidine base.

42
Q

What are the two steps of polypeptide synthesis ?

A

Transcription and translation

43
Q

What is DNA profiling?

A
  • also known as DNA fingerprinting, is a technique that allows scientists to determine inheritance patterns between individuals.
  • the technique analyses variable number tandem repeat sequences (VNTRs) that are specific to each individual.
44
Q

What Is Autosomal dominant inheritance?

A
  • When a trait is determined by the expression of a dominant allele
  • This means the phenotype will always be expressed over the other allele inherited.
  • Example of diseases passed by ADI include muscular dystrophy and Huntington’s disease
45
Q

What is Autosomal recessive inheritance?

A
  • The pattern of inheritance where two recessive alleles are required to be inherited in order for a trait to be phenotypically expressed
  • They are less prevalent in a population and may skip generations
  • examples of diseases include anaemia and cystic fibrosis
46
Q

What is co-dominance?

A

When both alleles in a gene pair are fully expressed
For example when an offspring inherits a A allele from one parent and a B allele from another parent both are expressed phenotypically in the AB blood type

47
Q

What is Incomplete dominance?

A

When an allele for a certain trait is not completely expressed over it’s paired allele
Resulting in the creating of a third phenotype which is a blend of the phenotype for both alleles
An example of incomplete dominance is pink flowers which are a result of cross breeding red and white flowers

48
Q

What is DNA sequencing?

A

Identifying the sequential order of nucleotides in the human genetic material.
- used to predict patterns of inheritance.

49
Q

What is examining frequency data definition?

A

Analysing the DNA sequence for specific genetic markers,enabling scientists to clearly distinguish between individuals in a population

50
Q

How is blood type inheritance determined?

A

Blood type in inheritance is determined by a mix of simple dominance and co-dominance there are two genes that determine this:

  • The gene for antigens present on blood cells (A, B, AB, or O)
  • the gene for Rhesus factor (positive or negative)
51
Q

What is single nucleotide polymorphism?

A

A change of a single nucleotide at a specific position on the genome, this may be a substitution (eg A for G), insertion (adding a new nucleotide) or deletion (removing a nucleotide)

52
Q

How common is single nucleotide polymorphism?

A

SNPs account for more than 90% of all differences across the human population they occur on throughout our genomes on average once in every 300
They are a key driver in evolution

53
Q

What is genetic conservation management?

A

The study of how diverse different species gene pools to determine how stable the population is.

54
Q

What is a haplotype?

A

A group of tightly-linked alleles inherited from a single parent.

55
Q

What is a Haplogroup?

A

A group of haplotypes which share a common SNP.

56
Q

When does DNA replication occur?

A

DNA replication occurs during the interphase of cell division.

57
Q

What is the effect of DNA replication effect on the continuity of species?

A

By copying the genetic material of a cell, replication ensures information important to the survival of a species is transferred down through generations.

58
Q

Why must DNA replicate prior to mitosis and meiosis?

A

If DNA were not replicated before mitosis and meiosis, cell division would halve the amount of DNA and resulting cells would die due to inadequate amounts of genetic information.

59
Q

How is the process of DNA replication initiated ?

A

The enzyme helicase breaks the hydrogen bonds between the nitrogen bases-unwinding and separating completely DNA strands.

60
Q

Explain the process of DNA replication following the separation of complementary DNA strands

A
  • RNA primers bind to ends of strands, signalling starting point of replication.
  • DNA polymerase binds to separated DNA strands at primer sites beginning to add new complementary base pairs.
  • DNA polymerase attaches to the end of the DNA segment, completing two identical strands which recoil into the double helix.
61
Q

Explain the cause of the lagging strand in DNA replication?

A

DNA is replicated in the 5’ prime to 3’ prime direction, as DNA is anti parallel replication will be continuous for one strand-leading strand, and discontinuous for the other strand-lagging strand.

62
Q

Define transcription in relation to polypeptide synthesis

A

Transcription is the process of turning genetic information stored in the DNA into mRNA.

63
Q

Explain the process of transcription in polypeptide synthesis.

A
  • Helicase unwinds a a small region of DNA
  • RNA polymerase synthesises an mRNA strand, using DNA strand as a template and matching free-floating complementary bases
  • terminator sequences end the transcription of DNA and the mRNA molecule is released
64
Q

What is the order of mitosis?

A 
Interphase 
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
65
Q

Define translation in relation to polypeptide synthesis.

A

Translation is the process of turning information encoded as mRNA into a polypeptide.

66
Q

Where does translation occur ?

A

Translation takes place in the endoplasmic reticulum.

67
Q

Explain the process of translation in polypeptide synthesis.

A
  • mRNA attaches to a ribosome
  • ribosome matches complementary tRNA molecule to mRNA -codon/anticodon sequence
  • subsequent tRNA molecules attach forming a polypeptide bond
  • when stop sequence is reached, ribosome release mRNA and polypeptide molecules
  • polypeptide folds and undergoes post-translation modifications - results in mature protein
68
Q

Identify the difference between DNA in prokaryotic and eukaryotic cells.

A

Eukaryotic cells have a nucleus in which DNA is stored, wound tightly around proteins called histones.
Prokaryotic cells do not have a nucleus but instead have chromosomal DNA found in the cytoplasm and additional chromosomal segments of DNA called plasmids.

69
Q

What is the importance of polypeptide synthesis to the function of organisms?

A
  • Polypeptide synthesis produces proteins essential to the structure and function of cells and organisms.
  • Protein interactions facilitate the high degree of coordination required in multicellular organisms.
  • increases complexity of organisms through introducing variation, increasing survival.
70
Q

What are the components of amino acids ?

A

Amino acids are organic compounds which have a central carbon, bound to an amine group, a carbonyl group, a hydrogen and a R-group (which varies in each type of amino acid).

HSC Biology (2022) (4 decks)

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