B5 Flashcards
Describe the nucleus
🟡Contains the genetic material of an organelle
🟡present in every cell
Describe the genetic material
🟡contains all the DNA and genes coding for specific proteins in the body
What is a genome?
All the genetic material of an organism
What is a gamete?
The sex cells (haploid cells)
A sperm or an egg
What is a chromosome?
Condensed tightly packed DNA around histone proteins
What is a gene?
A section of DNA that can code for a PROTEIN
What is an allele?
Different versions of the same gene
What is a dominant allele?
A form of a gene where only one copy is needed to be expressed as the genotype
What is a recessive allele?
A version of the gene where two copies are needed for it to be expressed as the genotype
What is meant when an organism is homozygous?
When an organism has two copies of the same allele
What is meant when an organism is heterozygous?
The organism has two different versions / alleles for the same gene
What is the genotype?
The genes present for a trait
What is a phenotype?
The visible and physical characteristic
What is discontinuous variation?
Variation that produces distinct categories
Eg( hair colour, eye colour, blood groups)
What is continuous variation?
Variation that cannot be placed into distinct categories and instead produces a spectrum
Eg(height, weight)
What impacts the development of a phenotype of an organism?
The genomes and it’s interaction with the environment
How do variants arise?
Random Mutations in the genetic code
What are the three possibilities of a mutation?
🟢no affect on the phenotype
🟢influence the phenotype
🟢 determine the phenotype
How do genetic variants influence the phenotype in coding DNA?
🟣The mutation will change the sequence of the amino acids in the protein changing the structure
🟣this will affect the activity of the protein
Eg. Enzymes (active site)
How do genetic variants influence the phenotype in non- coding DNA?
May stop transcription and alter the expression of genes
What are some pros and cons of asexual reproduction?
✅can produce offsprings quickly
✅if parent is well adapted then the offspring shares these characteristics
❌ no variation, so offsprings are susceptible to the same environmental pressures as parents
What are some pros and cons of sexual reproduction ?
✅variation leads to adaptations, so can cope in environmental pressure-population can continue
❌slower, so less offspring are produces
Explain the terms haploid and diploid cells
🟤Haploid cells have half the number of chromosomes in them.
Normally sex cells
🟤Diploid cells have the normal amount of chromosomes in them
What is the role of meiosis cell division?
🟪halves the number of chromosomes to for gametes
🟪maintains diploid cells when gametes combine
🟪a source of genetic variation
What is the end product in meiosis?
4 non - identical cells from one cell.
Cells in reproductive organs divide to form gametes
Describe meiosis
🔴cell makes copies of it’s chromosome, double the genetic info (46-92)
🔴the cells then divide (92-46)
🔴divides again (46-23)
🔴these cells are called gametes - haploid cells and are genetically different because chromosomes were shuffled in the process
Describe single gene inheritance
A trait linked to one gene pair that consists of two alleles
What are the sex genes determination ?
Ovaries contain the X chromosome.
Sperms contain either an X or Y chromosome.
XX is female
XY is male
Describe the role of 23 pairs of chromosomes
22 control characteristics, each pair look very similar
The 23rd carries sea determining gene , the two chromosomes look different to each other (y smaller than x)
What is polygenic inheritance?
Multiple gene interacting rather than a single gene to form a characteristic (phenotype)
What did Mendel discover?
🔵offsprings have some characteristics that their parents gave because they inherit hereditary units (genes)
🔵one unit is received from each parent
🔵units can be dominant or recessive and cannot be mixed together
What experiment did Mendel do?
Pea experiment, he noticed that height and colour were passed on to offspring
Is a population of species all the same?
No there is extensive genetic variation due to mutations
How does the development in biology impact classification systems?
🕝Before the artificial class system was used (human judgments and observations was used)
🕧 now natural classification is used using phylogenetics
What advances in biology lead to natural classification (phylogenetics) ?
🔸improvements in microscopes
🔸DNA evidence
🔸studies of biochemistry
What is phylogeny?
How does a phylogeny tree work?
The similarities and differences in DNA
🌳the closer the branches are the closer they are related
How does evolution occur through natural selection?
🔁random mutations occur between organisms
🔁if the mutation provides a survival advantage in the environment,the organism is more likely to SURVIVE and REPRODUCE.
🔁less well adapted organism die -“survival of the fittest “
🔁they pass on the advantageous gene
🔁this process occurs over many generations
What is evolution?
The change in inherited characteristics of a population over a period of time through a process of natural selection which may result in the formation of a new species
What is speciation?
The genetic variants make a population of species so different they they can no longer interbreed to produce fertile offsprings . This results in a new species
How do fossils show evidence for evolution?
🟢closely related organisms have evolved from the same ancestor
🟢 the simpler organism are found in older rocks, more complex organisms found in newer rocks
How would you answer a question asking why a characteristic has increases in a population?
- Identify the adaptation and how to helps the organism survive
2.explain how the adaptation helps the organism survive and reproduce so it can pass on the allele coding for the characteristic to the next generation - State how this increases the phenotype in the population
How does antibiotic resistance in bacteria show evidence for evolution?
Bacteria reproduces at a very fast rate
🦠Exposure to antibiotics creates selection pressure.
🦠Those with the antibiotic resistant gene survive and others die
🦠They reproduce and pass on the advantageous gene
Showing how those with antibiotic resistance become prominent within a population very quickly
How did the work of Wallace and Darwin contribute to evolution ?
🔺Wallace focused on speciation and how , physical isolation leads to different advantages for different environments
🔺Darwin focussed on survival of the fittest
What is a seedbank?
Buildings in which seeds are stored so that new plants may be brown in the future, even if naturally plants become extinct. This helps maintain biodiversity, a wide range of different species in an ecosystem.
What two scientists contributed their thoughts to evolution by natural selection?
Darwin and Wallace worked INDEPENDENTLY, in different islands , discovering different things
In the name ‘swima bombiviridis’.
What does the ‘swima’ represent?
What does ‘bombiviridis’?
🔵The first name is the genus
🔵the second name is the species
Why were people against Charles Darwin’s ideas on evolution?
🟡it want against religious belief’s
🟡there is insufficient evidence
