Module 5: Heredity Flashcards
Why is reproduction important?
It is a fundamental evolutionary process which has allowed for the continuity of life and species
What are the two main types of reproduction?
Asexual and sexual
What does sexual reproduction involve?
Two parents producing unique offspring
What occurs in sexual reproduction?
The meeting of special sex cells called gametes
What is an advantages of sexual reproduction?
Provides genetic diversity
What is a disadvantage of sexual reproduction?
Lots of time and energy required creating vulnerability to predators
How many chromosomes do humans have?
46 chromosomes arranged in a homologous pair
What does diploid mean?
2 sets of chromosomes
What does haploid mean?
1 set of chromosomes
What chromosomes do offspring inherit?
One set from mum and the other from dad
How is a zygote formed?
Fusion of haploid gametes
What are hermaphrodite?
Bisexual animals meaning they have both female and male parts
When is hermaphroditism good?
For species with low populations or non-mobile species
What is a disadvantage of hermaphroditism?
Requires a larger amount of energy expenditure
Where can fertilisation occur?
Externally or internally
What is external fertilisation more suited to?
Aquatic organisms
What is internal fertilisation more suited to?
Terrestrial organisms
What is done to increase the success of external fertilisation?
Synchronisation, mating behaviour and release of a large amount of gametes
Does external fertilisation include parental care?
No
What is an advantage of external fertilisation?
Wide dispersal of young
What is an example of external fertilisation?
Staghorn coral
How do Staghorn coral successfully undergo external fertilisation?
Shed million of gametes into the sea
Environmental cues help synchronise reproductive cycle
Pheromones also released with gametes to stimulate nearby coral
What is the benefit of internal fertilisation?
Protects gametes from dehydration and developing young from predators
How does reproduction in reptiles occur?
Eggs are fertilised internally and then deposited outside
What protection do most reptile eggs have?
A soft but tough leathery shell
What protection do only a few reptile eggs have?
Some like turtle eggs have a hard shell
Where does courtship take place for birds?
In flight or on the ground
Where does copulation occur for birds and what is its disadvantage?
Takes place on the ground making them vulnerable to predators
How do birds copulate?
Since male birds do not have a penis they instead rub their cloacas together with the female bird
What shell forms around bird eggs?
Calcium carbonate shell
Do birds show parental care?
They incubate their eggs and exhibit parental care after they hatch
What are the three subclasses of reproduction for mammals?
Monotremes, marsupials and eutherians
What are monotremes?
Mammals like platypus and echidna that have internal fertilisation and then lay eggs
Do monotremes express parental care?
Young hatchlings obtain milk from mammary glands
What are marsupials?
Mammals like kangaroos that develop internally for a short time and continue their embryonic development in a pouch
What is the reproduction cycle called in marsupials?
Embryonic diapause
Why is embryonic diapause beneficial?
It is a strategy to increase chances of survival
What are etherians?
Placental mammals such as humans where embryonic development occurs inside the body in the uterus
When does a placenta develop?
Once an embryo has implanted into the uterine wall
What does a placenta do?
Supplies nutrients and oxygen and removes wastes from the baby
What is it called when live young are born?
Viviparous
What is it called when young are born from eggs?
Oviparous
What is an advantage of eutherian reproduction?
Mature live young are born increasing their chance of survival
What does reproduction in plants rely on?
External agents to carry gametes also known as pollinating agents
What are the reproductive organs of plants?
Flowers
What is the male reproductive system in plants called?
Stamen
What are the parts of the stamen?
The anther and filament
What is the anther?
Where pollen grains are formed
What is the filament?
The stalk that carries the anther
What is the female reproductive system called in plants?
The carpel
What parts are there to the carpel?
Stigma, style and ovary
What is the stigma?
The sticky top surface of a flower to which the pollen adheres
What is the style?
It is what joins the stigma to the ovary
What is the ovary in plants?
Where the ovules are formed
What is pollination dependent on?
Dependent on wind, water and animals
What are the two types of pollinations?
Cross pollination and self pollination
What is an advantage of cross pollination?
It ensures greater variation in offspring
What is an advantage of self pollination?
It requires less energy
Which form of pollination is favoured ?
Cross pollination
How do plants account for the inefficiency of wind pollination?
Lots of pollen is produced
What is one method plants use to reduce pollen wastage?
They use flowers and nectars to attract animals
How does fertilisation occur in plants?
Sperm cell by the pollen tube fuses with ovum inside the ovule
Where do fertilised ovule develop in plants?
In the ovary
What does an ovule become in a plant?
An ovule containing an embryo becomes a seed and the ovary becomes its fruit
What are the two main types of fruits produced during reproduction in plants?
Dry fruits and fleshy fruits
How do dry fruits increase distribution?
They have explosive mechanism and are light
How do fleshy fruit increase distribuiton?
Animals eat them and then discrete the seeds
What is germination and when does it occur?
It is when a seed starts growing when it is in good conditions
What is a radicle?
A young root which grows during germination that absorbs water
What is a plumela?
A young stem that develops during germination and grows green leaves for photosynthesis
What does asexual reproduction involve?
One parent required to create genetically identical offspring
Where is asexual reproduction most common?
In unicellular organisms
What are some advantages of asexual reproduction?
Quick reproduction, competitive advantage if in suitable environment, uses less energy
What is a disadvantage of asexual reproduction?
Particularly vulnerable to sudden changes in environment
What are vegetative organs?
Organs such as bulbs, tubers, rhizomes and suckers
What are perennating organs?
Underground organs such as roots
What are the benefits of perennating organs?
Allow plants to survive harsh conditions and when separated give rise to new plants
What are runners in plants?
Long, thin, modified stems that grow along the surface
What is an example of a plant that uses runners as a method of reproduction?
Strawberries where leaves, flowers and roots are produced at nodes
What are rhizomes?
Underground horizontally modified stems
What is an example of a plant which uses rhizomes as a method of reproduction?
Ferns
What are suckers?
Roots of some plants which produce modified roots known as sprouts
What is an example of a plant that use suckers as a means of reproduction?
Blackberry
What are apoximis?
Plants that produce offspring from special generative tissue
What do apoximis create?
Gametes or leaf tissue
What is an example of a plant that uses apoximis as a means of reproduction?
Kangaroo grass
What is budding?
When an adult organism gives rise to a small bud
What does a bud do once reaching a certain size?
Separates from the parent and grows into a new individual
What are some examples of organisms that undergo budding?
Yeast, jellyfish and brain coral
What happens as a bud is forming?
The DNA duplicates and then the nucleus divides with one half moving into the bud
How long does budding continue for?
As long as there is sufficient nutrients
What is an advantage of budding?
If there is no change in the environment it will be highly suited to it
What is a disadvantage of budding?
They are not very resistant to change in the environment
What is the main method of reproduction for bacteria and protists?
Binary fission
What happens during binary fission?
Genetic material is replicated and then split in two
What is an advantage of binary fission?
Rapid population growth
What is a disadvantage of binary fission?
No genetic variation
How does binary fission occur in bacteria?
DNA attaches to opposite ends of the cell membrane and a new cell wall is synthesis in the cell cleavage
How does binary fission occur in protists?
Involves mitosis and the formation of a spindle
What are spores?
Spores are tiny unicellular reproductive cells
What are spores produced by?
Produced by structures known as sporangia
What makes spores different to gametes?
They do not have to fuse with a cell to produce an individual
What is the structure of a fungus?
Hyphae form the main structure of the fungal body known as mycellium
What are spores developed from?
Haploid nuclei
What is an advantage of spores?
Extremely light so can be spread wide by wind
How do fungus reproduce if conditions are unfavourable?
Sexually
What is the purpose of manipulating reproduction in agriculture?
To improve the quality and yield of food
What is reproductive technology?
Any use of technology to assist and improve reproduction
What can be done with reproductive technology?
Artificial insemination and embryo splitting
What are sex hormones responsible for?
The development of reproductive organs
What are breeding seasons?
Involves periods of female fertility being limited to once or twice a year
What are continuous breeders?
Females that have fertility cycles that repeat throughout the year
What are the three main sex hormones?
Androgens, oestrogens and progestogens
What are androgens?
Male hormones that control the development and functioning of male sex organs
What type of androgen is secreted in the testes?
Testosterone
What does testosterone do?
Plays a key role in sperm production
What are oestrogens?
Female hormones that control the development and functioning of female sex organs
What is the main function of oestrogen?
Ovarian functioning and fertility in females
What are progestogens?
Female hormones that play a key role in pregnancy
What is the most common progestogen?
Progesterone
What do oestrogen and progesterone regulate?
Gamete production in ovaries, preparing the uterus for implantation, menstruation and maintenance of pregnancy
What are the two types of gonadotropic hormones secreted by the pituitary gland?
Follicle stimulating hormones (FSH)
Luteinising hormone (LH)
What does FSH do?
Stimulates the maturation of follicles in ovaries
What does LH do?
Promotes final maturation of ovarian follicle, ovulation and development of corpus luteum
When do females get there eggs?
Female babies are born with all the eggs they will ever produce
How does an ova mature?
It becomes surrounded by a single layer of cells that begin to divive
How often on average does the ovarian cycle repeat?
Every 28 days
How does a follicle mature?
Follicle cells secrete fluid pushing eggs to one side of the follicle which then move to the surface creating a bulge
What is a matured follicle called?
Graafian
What hormone is produced during the follicular phase?
There is a surge in LH production
What does the surge in LH lead to in the follicular phase?
Causes ovulation and stimulates the next phase of the ovarian cycle
How long does the luteinising phase last?
Around 14 days
When does the luteinising phase begin?
After ovulation
What happens during the luteinising phase?
The burst follicle enlarges and changes colour building up a yellow protein lutein
What is the build up of lutein in the follicle called?
It is called the corpus luteum
What does the corpus lutuem do?
Secretes progesterone preparing the body for pregnancy
What starts the menstrual cycle?
Day one is menses which is when the lining of the uterus breaks down
When does the follicular phase start and end?
Starts on the first day of menses and ends at ovulation
What occurs during ovulation?
An egg is released
What does progesterone produced by the corpus luteum do?
Prepares the lining in the uterus for implantation
What hormones does the placenta produce?
Progesterone, oestrogen and HCG
What does LH stimulate in males?
The production of testestrone
What does FSH stimulate in males?
The production of a protein to maintain testestrone levels
What does the hormone inhibin do in the male reproductive cycle?
Reduces levels of FSH in the body
Where and how are sperm produced?
Produced by meiosis inside sperm tubules in the testes
What is the structure of a sperm?
Sperm head contains a haploid nucleus and long tail moves side to side
How many sperms enter the female reproductive system?
Half a million
How long can sperm survive in the female reproductive system?
For a couple of days
How are sperm attracted to the egg?
By rheotaxis which is the movement through fluid
What are the three layers of the egg a sperm has to get through?
Corna radiata, ona pellucida, cell membrane
What prevents other sperms from entering the egg after one has already penetrated it?
Surface proteins
What is a fertilised egg called?
A zygote
What happens to the corpeus luteum when a zygote implants?
It continues to grow and secreting hormones
When does the placenta do after three months?
It takes over the role of secreting hormones
When does the ovarian cycle usually resume after pregnancy?
After the mother stops breastfeeding
What does the placenta do?
Carries oxygen and nutrients from the mother to foetus and removes waste
What are the two things that must occur for birth to occur?
Uterus contractions and the tissue of the cervix must soften so that it can dilate
What hormones initiate labour?
Prostaglandins secreted by the uterus wall
What does oxytocin promote during labour?
Coordinated contractions and softens the cervix
What does relaxin do during labour?
Further aids in the softening of the cervix
What does the decrease of progesterone and oestrogen do during labour?
Promotes stronger contractions
What is mitosis responsible for?
Growth of multicellular organisms, repairing damaged tissue, asexual reproduction and genetic stability
What does meiosis result in?
Formation of gametes
What are the two parts of meiosis?
Meiosis 1 - diploid cell divides into haploid cells with half chromosomes
Meiosis 2 - cell divide again resulting in four haploid cells
What are the five main phases of the cell cycle?
G1 - gap phase for cell growth before DNA replication
S - synthesis during which DNA replicates (interphase)
G2 - second gap phase when enzymes check duplicated chromosomes
Mitosis - division of the nucleus
Cytokinesis - separation of the two cells
What are the four phases of mitosis?
Prophase, metaphase, anaphase and telophase
What occurs during prophase?
DNA separates into chromosomes containing two copies of DNA
What occurs during metaphase?
Chromosomes line up in the centre and spindle fibres attach
What occurs during anaphase?
Sister chromatids separate to opposite ends of the cell
What occurs during telophase?
Chromosomes gather on opposite ends of the cell and the nuclei form
Where else can DNA be found that is not in the nucleus?
In organelles such as mitochondria and chloroplast
When do organelles replicate?
After cell division they replicate independently
Who was the first scientist to identify DNA?
Miescher
What did Watson and Crick use to construct the DNA model?
Chemical and X-ray evidence
What is the Watson and Crick DNA model?
Two stranded molecules with paired bases twisted into a helix
What did crick realise about the backbone?
That the sugar phosphate backbone is antiparallel to the other
What are the two pairing options of bases?
Adenine (A) - Thymine (T)
Guanine (G) - Cytosine (C)
What holds the DNA strands together?
Weak hydrogen bonds
What are the two types of nucleic aicds?
DNA and RNA
What chemicals are in nucleic acic?
Carbon, hydrogen, oxygen, nitrogen and sometimes phosphorus
What are nucleic acids?
Polymers made from monomers called nucleotides
What is a nucleotide made from?
Ribose (RNA) or deoxyribose (DNA), phosphorus and nitrogen
What is DNA and what does it do?
Main chemical in the nucleus that stores genetic info that controls the cells and is responsible for transmitting inherited information
What is RNA?
Is a nucleic acid found in small amounts in the nucleus and in large amounts in the cytoplasm
What is a key difference between RNA and DNA bases?
RNA has the base uracile (U) instead of thymine (T)
What are the three types of RNA?
Messenger RNA - mRNA
Ribosomal RNA - rRNA
Transfer RNA - tRNA
What does mRNA do?
Carries info from the DNA to the cytoplasm
What does rRNA do?
Brings mRNA and tRNA together during translation
What does tRNA do?
Translates mRNA messages into proteins
What is the first step of DNA replication?
Helicase causes the DNA helix to progressively unwind
What is the second step of DNA replication?
DNA unzips from the bottom creating a replication fork exposing the nucleotide bases
What is the third step of DNA replication?
A primer attaches to the DNA and DNA polymerase III adds nucleotides to continue the synthesis
What are the two strands of DNA doing?
They run antiparallel and have either a 3’ end or 5’end
From where are nucleotides always added?
From the 3’ end
What is the leading strand and how are nucleotides added to it?
They end with 3’ end so nucleotides are added in long chains
What is the lagging strand and how are nucleotides added to it?
They end with 5’ end so nucleotides are added in chunks
What are the chunks added to the lagging strand known as?
Okazaki fragments
What does the enzyme ligase do?
Forms one continuous strand of the lagging strand
What is the fourth step of DNA replication?
Replication errors are identified and corrected by DNA polymerase I
What are natural errors in DNA replication known as?
Spontaneous mutation
What are errors in DNA replication caused by exposure to the environment called?
Mutagenic mutations
What are environmental factors that cause errors in DNA called?
Mutagens
What is DNA mismatch repair?
When polymerase I recognises mismatched base pairs and replaces them correctly
What can be the effects of mutations?
They can be harmful, beneficial or have no impact
Why is accurate replication of DNA important?
As the genes code for proteins that determine the functioning of the cell
What are 5 mechanisms to ensure genetic continuity?
Consistent replication before cell division
Orderly distribution of chromosomes
Successful fertilisation methods
Methods to ensure embryo survival
Natural selection
What are 2 mechanisms for genetic variation?
Mutation
Mixing of parental genes
What is the DNA like in prokaryotes?
Contain a single chromosome in a circular strand called a nucleoid
What non-chromosomal DNA do prokaryotes have?
One or more small rings of non-chromosomal DNA known as plasmids
What do plasmids do?
Code for features that are not essential to the survival of the cell
What is the structure of the DNA in prokaryotes?
Supercoiled and forms loops around a central protein
What is non-coding DNA known as?
Introns
What is coding DNA known as?
Exons
What is the structure of the DNA in eukaryotes?
Is linear and is wrapped around five main proteins known as histones
What are polypeptides?
Molecules made up of a chain of amino acids
What is transcription?
Process of creating RNA using RNA polymerase
What is the first step of transcription?
Part of the DNA unzips and the non-coding strand has the info for the protein
What is the second step of transcription?
The non-coding strand acts as a template for the mRNA to assemble
What is the third step of transcription?
The mRNA moves out of the nucleus and to the ribosomes
What is translation?
The synthesis of the polypeptide sequence from mRNA
What is the first step of translation?
Ribosomes move along mRNA and temporarily attach to tRNA
What is the second step of translation?
Amino acids on tRNA are linked by an enzyme forming a polypeptide chain
What is the third step of translation?
tRNA moves away from mRNA leaving a growing polypeptide chain
What is the fourth step of translation?
Polypeptide chain is processed and created into the final protien
What is the fifth step of translation?
mRNA is broken down to be reused
What is the shape of tRNA?
Clover leaf shape with at one end three unpaired bases called anticodons
How do tRNA work?
An anticodon attaches itself to its complimentary bases on the mRNA and an amino acid binds with the other end depending on the anticodon
What is the analogy for protein synthesis?
DNA is the operating system, mRNA is the software, tRNA is the machinery and the protein is the product
What is non-coding DNA responsible for?
It determines whether or not genes are read depending on how tightly its is wrapped around histones
What is phenotype?
The physical appearance, structure, behaviour and physiology
How can phenotype be influenced?
Can be influenced by genetics or factors in the environment
What is an example of a phenotype influenced by the environment?
Hydrangeas are different colours according the pH of the soil they are in
What colour are hydrangea flowers when in acidic soil?
Blue
What colour are hydrangea flowers when in basic soil?
Pink
What is the primary structure of proteins?
Arranged in linear chains
What is the secondary structure of proteins?
3D arrangement linked by hydrogen bonds
What is the tertiary structure of proteins?
More complex 3D arrangements
What is the quaternary structure of proteins?
2 or more polypeptide chains that are linked
What do fibrous proteins do?
Form structural components of cells and tissues
What is the structure of fibrous proteins?
Long and insoluble in water
What are some examples of fibrous proteins?
Collagen, elsatin, keratin
What is the structure of globular proteins?
Spherical in shape and compact and soluble in water
What is an example of a globular protein?
Haemoglobin
Where can structural protein be found?
In connective tissue like skin, bone and tendons
What do enzymes do?
They are involved in cellular metabolism and catalyse reactions such as chemical respiration and digestion
What do channel proteins do?
Regulate the intake and output of chemicals such as sodium ions
What do receptor proteins do?
Receive signals sent by hormones and neurotransmitter and act as markers allowing the body to recognise itself as self
What happens during crossing over?
Arms of pair of homologous chromosomes wrap around each other
What are the points of crossing over of chromosomes known as?
Chiasmata
What occurs at the chiasmata?
Arms of the chromosome break and exchange material
What are punnet squares?
A model used to represent inheritance
What can punnet squares be used for?
To predict possible outcomes
What is a test cross used for?
To determine the genotype of a phenotypical dominant thing as it can either be homozygous or heterozygous
What is a pedigree?
Traits expressed in a family over several generations with a minimum of three studied
What can a pedigree be used for?
To study the heredity patterns in families
What is the key usually to a pedigree?
Male - square
Female - circle
Trait present - shaded
What type of numbers should be assigned to each generation in a pedigree?
Roman numerals I, II, III
What type of numbers should be assigned to each individual in a generation?
Normal numbers 1, 2, 3
What makes a zygote female?
When an X chromosome is inherited from both parents
What makes a zygote male?
When an X chromosome from the mum and a y chromosome from the dad is inherited
What is sex linkage?
When the X and Y code for not only gender
Which chromosome X or Y can carry the allele?
X chromosome
In what gender do recessive disorders occur in more frequently?
In males
What is it called when an allele is present but not expressed?
A carrier
What is incomplete dominance?
The blending of features of the two alleles expressed
What is the notation for incomplete dominance?
A letter chosen for the gene and the allele is a subscript in the right top corner
What is codominance?
When both alleles are expressed creating a new phenotype
What is the notation for codominance?
Same as incomplete dominance but each allele is written with capital letters
What does multi-allelic mean?
When there are three or more alleles for a single gene trait
What is an example of multi-allelic trait?
Human blood type that has three alleles A, B and O
What is the dominance of the alleles for human blood?
A and B are codominant as markers are produced on RBC and and O is recessive as no markers are produced on RBC
What is population genetics?
Study of how the gene pool of the population changes over time
What is the gene pool?
Is the sum total of all the genes and alleles with a population
How can allele frequency be measured?
Number of copies of allele G in the population/ total copies of the gene G + g in the population
What does SNP stand for?
Single nucleotide polymorphisms
What does SNP refer to?
Individuals with different phenotypes
Where do most SNPs occur?
In the non-coding region hence are not observable
Why are SNPs important?
They are genetic markers used to distinguish individuals and can be associated with disease and disorder
What is genotyping?
Involves identifying genetic variation in individuals
What is sequencing?
Involves finding the exact nucleotide sequence
What is the sanger method?
A method for DNA sequencing
What is the sanger method known as?
dideoxy DNA (ddDNA) sequencing
What are the steps in the sanger method?
Isolate DNA from the cells, undergo the sequencing reaction, sort DNA fragments by length using capillary electrophoresis, analyse results using a computer
What is the maxam-gilbert method?
A method for DNA sequencing
What does the maxam-gildert method involve?
The chemical sequencing of DNA strands
Why is the maxam-gilbert method not used widely?
Due to its complex nature and its hazardous chemicals
What is DNA profiling also known as?
DNA fingerprint analysis
What is DNA profiling used for?
To identify and compare individuals by their DNA
What is DNA profiling a useful tool for?
In forensic investigations and paternity testing
What does PCR stand for?
Polymerase chain reaction
What does PCR do?
It increases the amount of DNA for testing
What is an ethical consideration of DNA sequencing?
Who owns the information once analysed
How do you know if an allele is sex linked dominant?
If a dominant father has female offspring with dominant traits
What base does uracil pair with?
Adenine
Is an artificially cloned mammal completely genetically identical?
No as there is DNA from the donated egg and the donated somatic cell
What type of response is sweating?
A nervous response
What type of response is vasodilation?
A nervous response
The rupture of an ovarian follicle occurs after a surge in which hormone?
Luteinising hormone (LH)
What is the response of an Australian plant to a named pathogen?
Basket grass responds to Phytophthora cinnamomi which is a fungus by producing hydrogen peroxide, reinforcing the cell wall and plant cell death to limit the spread
What is DNA sequencing?
Provides the order of bases and pairs
What is DNA profiling?
Gives information about the relatedness of an organism to other organisms
What is the main role of proteins?
To provide structure and support for cells
What does autosomal mean?
That the gene in question is located on one of the numbered chromosomes
Why is the process of polypeptide synthesis important?
It leads to the correct sequence of amino acids in polypeptides and proteins
What is population genetics?
The study of genetic variation within a population
What factors affect the gene pool?
Size population
Mutation
Natural selection
Genetic drift
Diversity of the environment
Migration patterns
What was used to compare koalas?
Haplotypes
What are haplotypes?
A group of SNP markers used to compare organisms
What is a monogenic disease?
A disease from a single gene in all cells of the body
What are polymorphisms?
When individuals have different phenotypes usually due to mutations
What is the newborn screening program?
Free genetic testing for newborns for SNPs associated with congenital diseases
What are the two main theories for human migration?
Multiregional hypothesis
Replacement hypothesis
Which theory is correct and what is the evidence?
Genetic studies have shown the multiregional hypothesis is correct
What are mutagenic agents?
Agents which alter DNA and cause mutations
What are some examples of chemical mutagens?
Ingested chemicals such as alcohol and environmental such as solvents
What do chemical mutagens do?
They are structurally similar to DNA bases and may be incorporated resulting in incorrect insertion of nucleotides
What are natural muatgens?
Mutagens present at normal level in the environment
What are biological muations?
Mutagens which are naturally occurring such as viruses and bacteria
What are non-biological mutations?
Mutagens which are naturally occurring such as metals
What is the arrangement of DNA in prokaryotic cells?
Single loop of DNA no nucleus
What is the arrangement of DNA in eukaryotic cells?
Strands of DNA in a nucleus
What is the role of progestrone?
Keeps the placenta functioning, maintains the uterine lining, regulates blood sugar levels, stimulates the growth of mammary
glands
How does progestrone levels change throughout pregnancy?
Normally rises during the first 36–38 weeks of the pregnancy, then fall towards the due date
What results in new alleles?
Mutation in the DNA gene
What does crossing over and and random segregation during meiosis lead to?
Creates new combinations of alleles, genetic variation
Where can mitochondrial DNA be inherited from?
Only females
How does mitosis contribute to continuation of species?
Mitosis assists the continuity of species by allowing growth and repair as well as asexual reproduction
What is independent assortment?
Homologous chromosome pairs are separated into daughter cells independently
What is random segregation of alleles?
During meiosis each parent passes an allele at random to their offspring resulting in a diploid organism
How is fertilisation important to the continuation of species?
Is essential for sexual reproduction
Involves the genetic input of of two different parents creating genetic diversity
Why is genetic diversity important?
It is important for natural selection and evolution in changing environments
Why is implantation important to the continuation of species?
It is important for placental mammals as it allows internal development so that young are born relatively developed
Why is hormonal control of pregnancy important to the continuation of species?
It ensure that the foetus is born when it has developed sufficiently to allow its survival
What does the hormone relaxin do?
Allows the expansion of joints and muscles of the mother
How many people in a population must have a SNP for it to be counted as an SNP?
At least 1% of the population
What is the larger structure in DNA?
Deoxyribose sugar
What is the smaller structure in DNA?
Phosphate
What is the function of proteins?
Are responsible for the functioning of cells as enzymes catalyse reactions
