Definitions Flashcards
1
Q
Define DNA
A
DNA (deoxyribonucleic acid) is the molecule inside the nucleus of cells that contains the genetic information responsible for the development and function of an organism.
2
Q
Define Nucleotides
A
DNA consists of simple repeating units called nucleotides which are made up of a sugar, a phosphate and a base. This includes the complementary base pairing rule.
3
Q
Define the base pairing rules
A
The complementary base pairing rule states that base pairs are always Adenine with Thymine (A-T)
Cytosine with Guanine (C-G)
4
Q
Define Genes
A
A gene is a section of DNA that contains the genetic code for a specific trait.
5
Q
Define Chromosomes
A
Chromosomes are long condensed structures of DNA found in the nucleus of cells, containing many traits. Each person has 46 chromosomes in each body cell (23 pairs).
6
Q
Define Alleles
A
Alternate forms and versions of a gene
7
Q
Define the DNA structure
A
DNA has a double helix structure (twisted ladder) and is comprised of repeating units called nucleotides.
8
Q
Define Traits
A
Features and charcteristics of an organism
8
Q
Define Homologous pair
A
Two chromosomes with the same genes.
9
Q
Give an example of an Allele
A
The allele for hair colour is blonde, brown, orange, etc.
10
Q
Give an example of a Gene
A
Hair colour, eye colour, etc
11
Q
Who do we inherit our sex from?
A
Females - X or X
Males - X or Y (they determine the biological sex of offspring)
11
Q
What is a karyotype test for?
A
A karyotype test can be used to check your cells to see whether you have a full set of 46 chromosomes as too little/much can cause health, growth and development issues.
12
Q
Define Genome
A
All the genetic information of an individual
13
Q
What are base sequences used for
A
The base sequence makes a gene grouped into threes, coding for amino acids. A long chain of amino acids is a protein
14
Q
Define Protein
A
Protein is what our bodies are made of and how they can can function, they also determine traits.
15
Q
Define Locus
A
The location of a gene on a chromosome
16
Q
Why do we have two alleles for every gene?
A
We inherit one from our mother (egg) and one from our father (sperm).
17
Q
Define Variation
A
Variation is the differences within a species, this can be continuous or discontinuous, inheritable or non inheritable. Variation can be due to our genetics and is impacted by the environment we live in.
18
Q
Define Phenotype
A
Our phenotype is determined by our genetics and the environment.
19
Q
Define Continuous variation
A
Variation with a range of values, eg skin colour, hair length.
20
Q
Define Discontinuous variation
A
Discontinuous variation has limited possible outcomes, eg right handed vs left handed.
21
Q
Define Inheritable variation
A
Variation caused by a change in the DNA that affects the reproductive cells (gametes) and therefore can be passed onto offspring.
22
Q
Define Non-inheritable variation
A
Variation that’s caused by environmental factors and therefore is unable to be passed down onto offspring (only affects somatic body cells)
23
Define DNA Replication
DNA Replication occurs in all cells to make a copy of the genetic material, this must occur before cell division.
24
Define the two types of Cell division
Mitosis
Meiosis
25
Define Mitosis
Mitosis is for growth and repair, growing organisms need to create more cells. Damage to cell results in cells being replaced to repair. Mitosis creates somatic cells (body cells). Mitosis is the process where the cell divides to form two new daughter cells that are identical to their parent cell (diploid cell → two diploid cells)
26
Define Meiosis
Meiosis is for the reproduction so that male and female cells can combine during fertilisation. This process creates gametes (reproductive cells). Meiosis is a process of cell division to produce reproductive cells (gametes) . 4 daughter cells are made that contain half the number of chromosomes of the parent cell.
27
How does DNA Replication work?
DNA molecule has to make a copy of itself before cell division, enzymes cause the strand of DNA to unzip and the base pairs of the other strand are replaced by new ones until two identical copies of each DNA molecule are formed.
28
Define DNA Replication
The result is two identical copies of DNA, each with an original parent strand and a new strand.
29
Define Diploid cell
Full set of chromosomes
30
Define Haploid cell
Half set of chromosomes
31
Define Crossing Over
During meiosis, homologous pairs of chromosomes come closer and swap different segments of the same genes. This leads to a new combination of alleles in the gametes (reproductive cells) which increases the variation of the potential offspring.
32
Define Independent Assortment
During meiosis, the homologous pairs of chromosomes randomly line up and divide into the gametes. The gametes will inherit one chromosome from each homologous pair. Each gamete receives a random assortment of chromosomes and therefore alleles.
33
How does Meiosis create variation
Crossing over and Independent assortment ensures that the 4 daughter cells are completely unique to each other and to the parent cell.
34
Define Mutation
A mutation is a permanent change in the base sequence of the DNA of an organism that results in the creation of new alleles being formed for a gene.
They are vital to a survival of a species.
Mutations occur randomly and spontaneously due to mistakes in DNA replication or due to exposure to mutagens.
35
Define Mutagens
A mutagen is a physical or chemical agent that changes the DNA of an organism and thus increases the frequency of mutations.
36
Define Inheritable Mutations in somatic cells
Mutations that occur in somatic cells (body cells) can cause cell death or cancer, but are not passed on.
37
Define Inheritable Mutations in gametes
Mutations that occur in gametes (sperm and egg) can be passed onto the offspring if they are the gametes that succeed in fertilisation. Gametic mutations will only get passed down if the sperm/egg with the mutation gets fertilised.
38
Define Asexual Reproduction
Asexual reproduction is the process of creating clones that are genetically identical to the parent. Only one parent is needed. It only uses mitosis as cell division to create the offspring.
39
What are advantages of Asexual Reproduction
Only one parent is needed
Requires less energy than sexual reproduction as no mate needs to be found and mating isn’t required
Much faster process
Predictable - you know what the traits are going to be for offspring
40
What are disadvantages of Asexual Reproduction
Asexually produced species are more susceptible to environmental changes and diseases
No variation within a species
Lack of diversity
41
Define Sexual Reproduction
Sexual reproduction occurs when the sperm from the male parent fertilises an egg from the female parent, producing an offspring that is genetically different from both parents. Both mitosis and meiosis occur.
42
Define Fertilisation
Gametes from two parents combine to form a new individual. These gametes have half a set of chromosomes from each parent.
43
Define Crossing over
During meiosis, pairs of neighbouring chromosomes cross over. They swap alleles meaning every gamete now has a unique combination of alleles.
44
Define Independent Assortment
Chromosomes line up randomly so each gamete receives a random combination of alleles.
45
What are the advantages of Sexual Reproduction
Increased genetic variation
Courting and mating rituals can ensure that more desirable traits are passed down to offspring
Higher chance of survival for the species during environmental changes as some individuals will be better suited to the change
46
What are disadvantages of Sexual Reproduction
Requires two parents
Takes longer and more energy
Can be dangerous competing with other males
Unpredictable outcomes
47
Define 'Dominant' alleles
‘Dominant’ alleles are always expressed when present. They are represented by capital letters.
48
Define ‘Recessive’ alleles
‘Recessive’ alleles are expressed if they are the only allele present. They are represented by lowercase letters.
49
Define Genotype
Genotype refers to the combination of alleles an organism has
50
Define Phenotype
Phenotype refers to the physical feature that we observe. Your phenotype is a combination of your genotype AND the environment.
51
What are the three different genotypes
Homozygous dominant
Homozygous recessive
Heterozygous
52
Define Homozygous dominant
Two of the same dominant alleles (capital letters)
53
Define Homozygous reccessive
Two of the same recessive alleles (lower case)
54
Define Pure breeding
Purebred animals are individuals who are homozygous for a particular trait.
Animal and plant breeders often want purebred stock. This is because the organism has no hidden genetic characteristics that may be undesirable.
When pure breeding individuals cross they will always produce offspring with the same genotype as the parents.
55
Define Heterozygous
Two different alleles (Upper case and lower case)
56
Why do we use Punnet Squares?
A tool that biologists can use to predict the combination of alleles that offspring will inherit from their parents are called Punnett Squares.
57
Why do we use Pedigree Charts
These are charts that show the inheritance of a trait or health condition through generations of a family.
58
Why do we do DNA analysis?
To find out if people (or other organisms are related) e.g. paternity testing
To find out what genes are present on which chromosomes
To investigate forensic evidence at a crime scene eg DNA can be left at a crime scene, which can be linked to suspects
To find out if a person has a genetic condition eg in NZ babies are tested for a condition call Phenylketonuria (PKU) when they are born
To find out if organisms are from the same species or are separate species eg some organisms look very similar and so to find out if they are separate genetic testing can clarify
Breeding programs eg cheetahs
59
Define the purpose of DNA analysis for Paternity/maternity testing
DNA testing can determine whether people are related (or not).
You inherit exactly half of your parent’s genes, so checking 16 genetic markers on both of you is enough to be 99.99% confident that someone is your parent/
60
Define the purpose of DNA analysis for breeding programmes
Genetic sequencing can be used to track healthy/harmful genes and to select individuals in an endangered population to mate with each other so that there is the maximum amount of genetic diversity.
This will help the species to survive.
61
Define how DNA analysis helps understand evolution
Molecular similarities provide evidence for the shared ancestry of life. DNA sequence comparisons can show how different species are related.
62
Define how DNA analysis helps medical interventions
To avoid cancers sometimes people have the parts of their body surgically removed preemptively. If they don't have the tissue they cannot get the cancer!
63
Define Natural Selection
Natural selection is a mechanism of evolution, it ensures that the only traits that help a species survive and reproduce get passed on to future generations.
64
Define Phylogeny
Phylogeny is the representation of the evolutionary history and relationships between groups of organisms.
65
Define Phylogentic trees
A phylogenetic tree is a diagram that represents evolutionary relationships among organisms. Phylogenetic trees are hypotheses, not definitive facts.
The pattern of branching in a phylogenetic tree reflects how species or other groups evolved from a series of common ancestors.
66
How do we see the relation of speceies in Phylogeny trees?
In trees, two species are more related if they have a more recent common ancestor and less related if they have a less recent common ancestor.
67
Define Emigration
Exit
68
Define Immigration
Enter
69
Define Migration
Migration is when an individual moves into or out of a population. Migration can bring in new characteristics (alleles and genes) and also remove them from a population. Organisms migrate for many reasons eg. For food, shelter etc.
70
Define gene flow
Gene Flow is the movement of individuals in and out of a population (and therefore their alleles). Individuals have a variety of alleles and by removing individuals this reduces the genepool variety. By adding individuals, new alleles are added. The exchange of genes between two populations (AA to aa)
71
Define Allele frequency
Allele frequency (similarities) between populations decreases as the physical distance between populations increases.
Populations in and closer to Africa have the highest rate of variation in their DNA today. Our traits are influenced by our geographic origins and environment. (e.g. nose shape, eye and hair colour)
Disease resistance in some cases is related to geographic origins. (e.g. sickle cell anemia and malaria)
72
Define genome
A genome is the complete set of genes or genetic material present in a cell or organism. Technology allows us to have this information and it helps us to understand different species.
73
Define Natural Selection
Natural selection is the mechanism of evolution where individuals in a population that are better suited to an environment survive and reproduce in greater number, passing on their desirable traits.
74
Define Appearance in Non-random Mating
If individuals mate by selecting for specific phenotypes, this can change the population. e.g. if a female peahens prefer peacocks with bigger, brighter tails, this may increase the frequency of alleles for bigger, brighter tails in the population.
One common form of mate choice, called ASSORTATIVE MATING, is an individual’s preference to mate with partners who are similar to themselves.
75
Define Assortative Mating
An individual’s preference to mate with partners who are similar to themselves.
76
Define Location in Non-random Mating
Another cause of NON-RANDOM MATING is physical location. In large populations spread over large geographic distances, not all individuals will have equal access to one another. Some might be miles apart while others might live nearby.
77
Define Population Bottleneck
A population bottleneck is an event that drastically reduces the size of a population.
The bottleneck may be caused by various random events, such as an environmental disaster, the hunting of a species to the point of extinction, or habitat destruction that results in the deaths of organisms.
78
Define Population
A group of organisms of one species that breed together and live in the same place at the same time.
79
What are the sources of Genetic Variation
Sexual reproduction:
Fertilisation
Meiosis (Independent assortment and Crossing Ove)
80
Define Mutations
Permanent changes in the DNA base sequence that give rise to new alleles
81
What affects variation in a population?
Natural selection
Population size
Migration (gene flow)
Non-random mating
82
Why is low genetic variation bad?
Low variation makes the species more vulnerable to environmental changes or random events e.g. diseases.
83
Why is high genetic variation good?
High genetic variation is an advantage.
When environmental changes occur some individuals may have favourable traits that make them more likely to adapt and survive. This is essential for the long term survival of the species.
84
What is genetic variation?
Genetic variation refers to the variety of genes within a population.
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