Biology: Module 5 - Heredity

HSC: Heredity

what are the five kingdoms

1. bacteria

2. protists

3. fungi

4. plants

5. animals

define reproduction

a biological process by which individual organisms (offspring) are produced from their parent or parents

why is reproduction neccesary?

A necessity for the continuity of species

• If new organisms weren’t produced, species would go extinct

what is asexual reproduction and some of its features

where an organism clones itself

• Only occurs in unicellular organisms

• Only one parent

• Genetically identical offspring

advantages of asexual reproduction

• Efficient form of reproduction

• Amount of time and energy to produce offspring is less

• Population sizes can increase rapidly in optimal environments

• No need for sexual partner

• Genetically identical offspring, so well suited for stable environment

disadvantages of asexual reproduction

• Rapid population growth can lead to overcrowding and increased competition

• Lack of genetic variation in a population can cause death of the population if conditions change

what is binary fission

• Produces two new daughter cells genetically identical to the parent

•  DNA needs to be replicated

• Has one circular piece of DNA → replication occurs in both directions around the circle until the whole chromosome is replicated

• Membrane pinches → two chromosomes move to opposite parts of the cell → new cell wall forms → bacteria replicates

why has the classification of living things changed over time

new organisms have been discovered 

what is the benefit of three domain of life system

• allows classification to go further and acknowledges a common ancestor

  • Shows how different kingdoms are related to each other

what is the benefit of the five kingdom classification

classify organisms based on their similarities and differences

what is the bacteria’s

1. cell type

2. cell wall

3. number of cells

4. mode of nutrition

5. reproduction

6. example

1. prokaryote

2. cell wall

3. unicellular

4. auto/heterotroph

5. asexual

6. salmonella

what is the protista

1. cell type

2. cell wall

3. number of cells

4. mode of nutrition

5. reproduction

6. example

1. eukaryote

2. cell walls - some have chloroplast

3. unicellular, colonial, multicellular

4. auto/heterotroph

5. a/sexual

6. euglena, algae

what is the fungi

1. cell type

2. cell wall

3. number of cells

4. mode of nutrition

5. reproduction

6. example

1. eukaryote

2. cell wall

3. multicellular

4. autotroph/decomposer

5. a/sexually

6. yeast, mushrooms

what is the plants

1. cell type

2. cell wall

3. number of cells

4. mode of nutrition

5. reproduction

6. example

1. eukaryote

2. cell wall with chloroplast

3. multicellular

4. autotrophic

5. a/sexual

6. grass, sunflower

what is the animalia

1. cell type

2. cell wall

3. number of cells

4. mode of nutrition

5. reproduction

6. example

1. eukaryote

2. no cell wall

3. multicellular

4. heterotrophic

5. human, tiger

what kingdoms participate in binary fission

bacteria - parent cell survives

protists - need to split their nucleus first, parent cell splits into two daughter cells

what type of reproduction is this?

asexual - binary fission

what is multiple fission

Nucleus divides repeatedly before the cell splits and then the cell splits multiple times from the parent cell to produce more than two offspring

what is this reproduction?

multiple fission

who participates in multiple fission

some protists

what is budding

• Asymmetrical division

• Where the nucleus reproduces and smaller buds split off from the parent cell after an uneven division of the cytoplasm

what is this type of reproduction

budding

what is fragmentation

Breaks into smaller pieces and allows regeneration of the whole organism from new pieces

what type of reproduciton is this

fragmentation

which kingdoms participate in fragmentation

Some multiple algal protists

Animals: annelids etc.

what is a mitospore

• Mitospores = reproduced asexually through mitosis

  • Haploid (n) reproductive cells

  • Capable of developing into an adult without fusion with another cell

  • Due to the parent organism being haploid

what is the benefit of spores as reproduction

Allow fungi to expand their distribution and colonise new environments

where are spores released from?

Released from the parent thallus: from outside or in a sporangium

what reproduction is this?

spores

what kingdoms uses spores to reproduce?

fungi, plants

what is parthenogenesis

• The development of an egg in the absence of fertilisation

• Can only occur in females

• E.g. reptiles, birds, insects, nematodes…

what is this reproduction

parthenogenesis

which kingdoms participate in parthenogenesis

animals

what is rhizomes and an example

• Root-like stems that grow horizontally under the ground. New shoots and roots form at the nodes, with shoots growing upwards to form new plantlets

• Lateral buds grow out to form new rhizomes

• E.g. ginger, irises, couch grass

what is a bulb and an example

• Form lateral buds from the base of the mother bulb, which produces new smaller bulbs or bulbels

• E.g. onions

what is stolons or runners and an example

• Horizontal stems that grow above the ground

• Tiny plantlets form along the stolon, and roots form where they touch the ground

• When the connection with the parent breaks, the new plant becomes independent

• E.g. strawberries

what are tubers and an example?

• Tubers = Swollen portions of an underground stem that store food so a plant can lie dormant over the winter

• Axillary buds (eyes) form over the surface of the tuber and produce shoots that grow into a new plant the following year

• E.g. potato

what are suckers and an example?

• New shoots that arise from the roots

• E.g. bananas, wattle tree

what is natural vegetative propagation

an asexual reproductive method used by plants

• The growth of specialised plant tissues that can grow into a new plant if separated from the parent

  • Doesn’t use seeds or spores

what are advantages and disadvantages of natural vegetative propagation

• Advantages: It can produce a rapid increase in the number of plants growing in a favourable area to outcompete other species

• Disadvantages: 

  • competition from sister and parent plants for resources (intraspecific competition)

  • Lack of genetic variation to protect population from disease and environmental changes

what is artificial reproduction

results in features of desirable plants that have been preserved from generations for commerical quantities

give three examples of artifical reproduction and a little description

1. Cuttings: a piece has been cut off a mother plant then caused to grown into a new plant sometimes through hormones that encourage new roots

2. Grafting and Budding: joining a stem piece or a single bud into a stem of a plant that has roots

• The stem piece (scion) and the plant with roots (rootstock)

3. Tissue Culture: tiny fragments of plants are treated with plant hormones in a sterile environment to stimulate the growth of a callus for new seedlings to grow

• Used to produce large number of identical seedlings

what is sexual reproduction

a combination of gametes to form a zygote

what are the advantages of sexual reproduction

• Fertilisation is less risky and the young are more likely to survive

• Unfavourable genetic variation is eliminated from population effectively

• Generates genetic variation during meiosis 

• Populations can adapt to changing conditions

• Improves evolution of the species

what are the disadvantages of sexual reproduction

• Slower reproductive rate

• Mates have to be found and accepted

• Potential for sexually transmitted diseases

• Uses a lot of energy

what are meiospores

• Sexual Reproduction of Spores = meiospores

how are meiospores produced?

• 2 haploid (n) cells fuse together → where two haploid nuclei coexist (plasmogamy)

• Haploid nuclei fuses together to create 1 diploid (2n) nucleus (karyogamy)

• Gametes of different mating types are produced → spores are disseminated into the environment (meiosis)

what is conjugation

Two individuals fuse and exchange genetic material

what reproduction is this

conjugation

how does angiosperms pollinate?

male pollen lands on female stigma —> tube grow to petrate surface of stigma > pollen tube carries two sperm cells to reach the ovule —> egg fuses with one sperm to form 2n cell/embryo —> other sperm combines with tissue to nourish embryo—. ovule develops into seed, leaves,roots, tissues —> ovary becomes matured fruit —> embryos lie in seeds until conditions are right to germinate

where does the male gametophyte stay and what is it

the pollen grain which contains sperm celles hled on the anther at the top of the stamen

what is the female gametophyte and where is it

the embryo sac that contains the egg held in an ovule in the plant’s ovary

label diagram

how do bryophytes reproduce?

• Have a reproductive structure that produces gametes in a specialised structure (gametophytes)

• Asexually reproduces through fragmentation, budding

• Sexually reproduces through releasing sperm from antheridin to swim in the egg 

• Spores are produces and dispersed to form new gametophytes

how do ferns reproduce

• Reproduce sexually through spores

• Spores released from underside of the fronds and develop into gametophytes, to produce sperms and eggs

• Sperm swims to egg to form new sporophyte

how do gymnosperms reproduce

• Have male and female cones

• Pollen is released from microsporangium to reach the female cone (sex organ)

• Male gametes get discharged and the male and female gametes fuse, fertilising to form an embryo and the ovule forms a seed

what is external fertilisation

When a male’s sperm fertilises a female’s egg outside of the female’s body

examples of external fertilisation

• E.g. female frog releases unfertilised eggs in water → male frog latches unto the back of the female → releases sperm into water → latching on the female ensures eggs and gametes are more likely to unite

• E.g. salmon, cod, frogs, aquatic invertebrate

advantages of external fertilisation

• More rapid and with larger quantities

• Female can continue to reproduce without waiting for the first young to develop

• Parents don’t spend energy for gestation and caring for the young

• Young are widely dispersed, reducing competition

disadvantages of external fertilisation

• More gametes need to be produced

• No control over the gametes once released

• Decreased chance of successful fertilisation - unless synchronised release of gametes

• Young usually need to fend for themselves

• Must take place in aquatic environment - otherwise gametes would dehydrate and can’t move

• Gametes and zygotes are exposed to predation, disease, environmental changes

what is internal fertilisation

• When the male transfers his gametes directly into the female’s body through a tube in his penis

  • The gamete union occurs within the body of the parent

• The chromosomes in the sperm pair with the egg’s to form a diploid zygote cell

  • The development of the zygote continues internally through mitosis, inside the females (mammals) or externally inside a shelled egg fed by yolk

• All terrestrial animals and some aquatic animals undergo internal fertilisation

what are advantages of internal fertilisation

• Can take place on dry land - the reproductive tract is always moist

• Less gametes have to be produced

• More likely to be successful because gametes are positioned close together in the tract

• Gametes and zygotes are protected from predation and diseases

• Developing young are fed and protected increasing their chance of survival

what are disadvantages of internal fertilisation

• Usually slower with fewer progeny

• Mating rituals and practices are more complex to reach sex

• Potential for STD through population

• Uses a lot of energy input

• Parental care of young may be lengthy

what is a placental mammal and e.g

• Have a longer gestation period

• Give birth to a developed young

Humans, horses, dogs, mice, seals

what is a marsupial mammal and e.g

• Give birth to underdeveloped live young

• Placed in a pouch to develop further

Kangaroo, brushtail possum, wombat, koala

what is a monotreme and an e.g.

• Lay eggs, oviparous

• The young develop in the eggs

Platypus, echidna

where are male gametes held in humans

• Paired testes are held inside the scrotum which produces and stores mature sperm continuously

  • Seminiferous tubules where sperm cells are formed

Epididymis stores the sperm cells

what is the purpose of the flagellum of a sperm

Have a flagellum to propel them through the female reproductive system towards the egg after copulation

when does spermatogenesis start?

during puberty and often continues throughout his life

what is this?

spermatogenesis

• what does Luteinising hormone (LH) do in males?

from the pituitary gland in the brain stimulates the secretion of testosterone in the testes

what is the uterus

where the fertilised egg goes to be implanted

what do the ovaries hold

oocytes (immature egg cells) until puberty and ovulation

what is the production of ova (oogenesis)

starts during foetal development —> is arrested during prophase I —>  During puberty, the ovarian cycles commence again, the pituitary hormones control the continuation and completion of meiosis I —> Meiosis II occurs, but is arrested until actual fertilisation occurs, and only continues once the egg is fertilised

four phases of ovulation

1. follicular

2. ovulation

3. luteal phase

4. menstruation

what is the follicular phase

FSH (follicle stimulating hormone) is secreted from anterior pituitary gland

• Stimulates growth in ovarian follicles

• The dominant follicle produces oestrogen: inhibits FSH secretion to → prevent other follicle growth

• Oestrogen begins to stimulate the thickening of the endometrium in the uterus for implantation

what is ovulation

• Oestrogen → stimulates anterior pituitary gland to secrete hormones → surge of luteinizing hormone (LH) → decrease in FSH

• LH causes dominant follicle to rupture and release a secondary oocyte ovulation

what is luteal phase

• Ruptured follicle develops into slowly degenerating structure called corpus luteum

  • Secrete high levels of progesterone, lower levels of oestrogen → thicken endometrium → inhibit FSH and LH

what is menstruation

• If fertilisation occurs, developing embryo will implant in the endometrium and release hormones to sustain corpus luteum

• If not, corpus luteum degenerates → oestrogen and progesterone levels drop → endometrium is eliminated as menstrual blood

• Another cycle begins → FSH rises

what are the hormones associated with each colour?

define fertilisation

• the fusion of two haploid (n) gametes to form a single diploid (2n) zygote cell

  • There are equal genetic contributions front he male and female for the zygote

what is the fertilisation event (5 steps)

1. Sperm injected into vagina, where it swims through the cervix to into the oviduct

2. Sperm uses enzymes to dissolve the protective layer around the egg to reach the cell membrane

3. The sperm binds to specialised proteins on the egg’s cell membrane to ensure that a sperm of the species fertilises the egg → its nucleus enters the cytoplasm

4. The egg’s surface changes to prevent multiple sperm nuclei from entering the egg

5. Fusion of the haploid egg and sperm nuclei result in a diploid zygote cell

what is implantation

• The zygote travels down the oviduct to reach the uterus

• The embryo has started with cleavage → and once it reaches the uterus ready for implantation it is a blastocyst (ball of cells)

what are the steps the zygote goes through to become gastrula

1. Cleavage: the single celled zygote is divided into hundreds of smaller cells by mitosis

2. Morula: embryo continues to divide, until a few days later it has 16 cells as it enters the uterus. It has unspecialised embryonic stem cells

3. Blastocyst: it still divides and becomes a blastocysts as the cells begin to differentiate, and by day 8 or 9 it implants to the wall of the uterus

   1. The outer layer of cells sends out projections into the endometrium that develops into the placenta

4. Gastrula: occurs over five days, where the blastocyst becomes a gastrula that has three different layers of cells → becomes embryo → foetus.

what is the placenta

outer layer cells of blastocyst form placenta - an exchange organ that brings foetus’ blood vessels in close contact with the mum’s without it being directly exchanged

- nutrients and waste diffuse across

what is FSH and where is it secreted from?

Follicle Stimulating Hormone (FSH)

Anterior pituitary

Promotes development of follicle and secretion of oestrogen

what is LH and where is it secreted from?

Luteinising Hormone (LH)

Anterior Pituitary

• Promotes ovulation

• development of corpus luteum

• secretion of progesterone

what is prolactin and where is it secreted from

Prolactin

Anterior Pituitary

• stimulates milk secretion

what is oestrogen and where is it secreted from

Oestrogen

Corpus luteum then placenta

• Develops placenta, foetal organs

• Promotes menstrual cycle

• Maintains uterine lining

• Increases blood flow to uterus and placenta

• Suppresses LH and FSH production

what is progesterone and where is it secreted form

Progesterone

Corpus luteum (for 6 weeks) then placenta

• Thickens endometrium to allow implantation

• Supports pregnancy

• Suppress contractions and lactation from preterm labour

what is oxytocin and where is it secreted from

Oxytocin

Posterior pituitary

• Helps contractions to occur

what is hcg and where is it secreted from

Human chorionic gonadotropin (hCG)

Placenta

• Maintains corpus luteum for it to produce progesterone to prevent menstruation

• Thickens endometrium

• Stimulates production of blood vessels in uterus

• Regulates ovarian hormones

what is relaxin and where is it secreted from

Relaxin

Ovary and placenta

• Relaxes ligaments in pelvis and widens cervix for childbirth

what are the hormones associated with these colours: hcg, oestrogen, progesterone

selective breeding is

humans manipulate gene pools of populations through deliberate selection of individuals for breeding

what is the process of selective breeding

1. Determine the desired trait

2. Interbreed parents who show desired trait

3. Select offspring with best form of the desired trait and interbreed them

4. Continue process until population reliably reproduces desired traits

what is gene linkage

• When not just the desired trait is selected for - can be inadvertently selected

• Genes that are located close together on a chromosome are said to be linked

  • Those genes usually stay together and are inherited

• E.g. Silver Fox = the genes related with “tameness” are carried on chromosomes linked with their ears, tails and colour of fur

why is selective breeding done in plants

• This is usually done to producing higher-quality food

• Results in larger, nutritious or more aesthetically pleasing food

examples of selective breeding in plants

• E.g. tomato, cereals, potato, wheat

• Maize was bred from a wild grass called teosinte - modern maize has larger cobs with more rows or larger kernels

what is polyploidy

• A condition where the cell nucleus has more than two sets of chromosomes where the genome is 3n or more

• Can occur naturally through errors in meiosis 

  • Gamete is 2n rather than n