Module 5 Flashcards
Define mitosis
Cell division resulting in two identical daughter cells (diploid) with the same number and kind of chromosomes as the parent
Define meiosis
Cell division resulting in four daughter cells (haploid gametes) each with half the number of chromosomes as the parent cell
Explain the process of sexual reproduction in animals.
- 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.
Explain the process of sexual reproduction in plants.
- 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.
How to plants replicate asexually?
Stem or roots sprout to form new individual organisms without the need for seeds.
Advantages and disadvantages of internal fertilisation in animals.
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 😬
Advantages and disadvantages of external fertilisation in animals:
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
Explain asexual reproduction in fungi.
- 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.
Explain sexual reproduction in fungi.
- 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.
Explain reproduction in bacteria.
Bacteria reproduces asexually via binary fission (mitosis):
- dna replicates
- a single cell splits via cytokinesis into two identical daughter cells
Explain the process of sexual reproduction in protists.
- 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.
Advantages and disadvantages of sexual reproduction.
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.
Advantages and disadvantages of asexual reproduction.
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.
Explain the process of fertilisation and implantation.
- 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.
Explain how oral contraceptives prevent pregnancy.
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.
How is selective breeding used for specific outcomes.
- Based on the understanding that phenotypes are hereditary so plants with desirable traits are pure or crossbreed over generations.
What are the benefits of artificial insemination in agriculture?
- gives farmers the ability to synchronise pregnancy’s
- can be used to pass on specific traits
- increases probability of successful fertilisation
What are the benefits of artificial pollination in agriculture?
- cross breeding of desirable traits
- ensures successful pollination
- does not rely on bees
How is genetic engineering used in agriculture?
- Allows for the manipulation of the genetic material of plants to create ideal traits.
What is the interphase
Cell replication is prepared as DNA is replicated to produce two copies of each chromosome
What is the prophase?
- duplicated chromosomes condense
- the strands of of the miotic spindle held together by the centromere divide the cell.
- the nuclear enveloppe breaks down
What is the metaphase?
- chromosomes becomes fastened to the centromere at the equator of the cell
- chromosomes line up along the equator
What is the anaphase?
- 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
What is the telophase?
- nuclear membranes from around each daughter cell
- the cell splits down the middle to form two identical daughter cells (cytokinesis)
What occurs during meiosis 2?
The chromatid pairs split into 4 single chromosomes creating 4 haploid cells.
Define haploid
Single set of unpaired chromosomes.
Define diploid
A cell containing two complete sets of chromosomes (one from each parent)
What is a genotype?
alleles present in an organisms chromosomes
What is a phenotype?
Outward appearance of an organism determined by alleles present
Influenced by:
Genotype
Interaction between genotype and the environment
Epigenetic factors
Define allele
Alternative forms of a gene ( in Latin it means rival)
Define gene
A section of DNA encoding a particular characteristic
What is the Watson/Crick model of DNA?
- 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.
Define Heterozygous
Different alleles in a gene pair
Pp pP
Define homologous
Identical alleles in a gene pair
pp PP
What is autosomal inheritance?
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
What is sex linkage inheritance?
When traits (alleles) are passed on the sex chromosomes (x or y) may either be x linked or y linked
What are the nucleotide bases?
A - adenine G - guanine C - cytosine T - thymine U - uracil (replaces adenine in RNA)
List the five components of DNA
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.
What are the three types of RNA?
Messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA ( rRNA, the site of protein synthesis).
Explain the role of the enzyme helicase in polypeptide synthesis.
Helicase is an enzyme that unwinds the DNA double helix by breaking the hydrogen bonds that connect the nitrogen bases.
What is the complementary base pair to adenine?
Adenine is a purine base that pairs with Thymine, a pyrimidine base.
What are the two steps of polypeptide synthesis ?
Transcription and translation
What is DNA profiling?
- 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.
What Is Autosomal dominant inheritance?
- 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
What is Autosomal recessive inheritance?
- 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
What is co-dominance?
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
What is Incomplete dominance?
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
What is DNA sequencing?
Identifying the sequential order of nucleotides in the human genetic material.
- used to predict patterns of inheritance.
What is examining frequency data definition?
Analysing the DNA sequence for specific genetic markers,enabling scientists to clearly distinguish between individuals in a population
How is blood type inheritance determined?
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)
What is single nucleotide polymorphism?
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)
How common is single nucleotide polymorphism?
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
What is genetic conservation management?
The study of how diverse different species gene pools to determine how stable the population is.
What is a haplotype?
A group of tightly-linked alleles inherited from a single parent.
What is a Haplogroup?
A group of haplotypes which share a common SNP.
When does DNA replication occur?
DNA replication occurs during the interphase of cell division.
What is the effect of DNA replication effect on the continuity of species?
By copying the genetic material of a cell, replication ensures information important to the survival of a species is transferred down through generations.
Why must DNA replicate prior to mitosis and meiosis?
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.
How is the process of DNA replication initiated ?
The enzyme helicase breaks the hydrogen bonds between the nitrogen bases-unwinding and separating completely DNA strands.
Explain the process of DNA replication following the separation of complementary DNA strands
- 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.
Explain the cause of the lagging strand in DNA replication?
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.
Define transcription in relation to polypeptide synthesis
Transcription is the process of turning genetic information stored in the DNA into mRNA.
Explain the process of transcription in polypeptide synthesis.
- 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
What is the order of mitosis?
Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
Define translation in relation to polypeptide synthesis.
Translation is the process of turning information encoded as mRNA into a polypeptide.
Where does translation occur ?
Translation takes place in the endoplasmic reticulum.
Explain the process of translation in polypeptide synthesis.
- 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
Identify the difference between DNA in prokaryotic and eukaryotic cells.
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.
What is the importance of polypeptide synthesis to the function of organisms?
- 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.
What are the components of amino acids ?
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).
