Module 5: Heredity Flashcards
(125 cards)
1
Q
Asexual reproduction
A
Requires only one parent. Parent cell replicates and divides to create genetically identical offspring.
2
Q
Sexual reproduction
A
Requires two parents. Haploid gamete cell from each parent produces genetically unique offspring.
3
Q
Disadvantages of sexual reproduction
A
- Energy costly
- Requires 2 parents
- Finding mate is time and resource consuming
4
Q
Advantages of sexual reproduction
A
- High genetic diversity
- Less vulnerable to environmental change
5
Q
Disadvantages of asexual reproduction
A
- Low genetic diversity
- Vulnerable to environmental change
6
Q
Advantages of asexual reproduction
A
- Energy efficient
- Requires only 1 parent
- No mating required
7
Q
Male plant reproductive organs
A
- Anther
- Filament
8
Q
Female plant reproductive organs
A
- Stigma
- Style
- Ovary
- Ovum
9
Q
Anther
A
Male plant reproductive part where pollen grains are formed.
10
Q
Filament
A
Male plant reproductive part. Stalk that carries an anther. Length of filament determines whether anthers are inside petals (insect pollination) or hanging outside (wind pollination).
11
Q
Stigma
A
Female plant reproductive part. Sticky top surface of flower to which pollen adheres. May be small and smooth (insect pollination) or large and feathered (wind pollination).
12
Q
Style
A
Female plant reproductive part that joins stigma to ovary.
13
Q
Ovary (plant)
A
Female plant reproductive part where ovules are formed.
14
Q
Budding
A
Form of asexual reproduction. Bud forms from parent, eventually separates to grow new individual.
15
Q
Advantage of budding
A
If no variation in environment, identical offspring are always adapted to surroundings.
16
Q
Disadvantage of budding
A
If environment changes, entire species may rapidly decline/die out.
17
Q
Binary fission
A
Splitting (fission) into two (binary). Main method of asexual reproduction in unicellular organisms. Basically cell division.
18
Q
Advantage of binary fission
A
Rapid population growth over short time in adverse conditions.
19
Q
Disadvantage of binary fission
A
No genetic diversity
20
Q
Spores
A
Unicellular reproductive cells produced by sporangia in organisms such as fungi, mosses and ferns.
21
Q
Parthenogenesis
A
Form of asexual reproduction involving the development of female (rarely male) gametes without fertilisation. E.g. bees
22
Q
Biological fitness
A
A measure of reproductive success based on the likelihood that alleles will be represented in future generations.
23
Q
How many chromosomes & pairs do humans have
A
- 46 chromosomes (23 pairs)
- 44 autosomes (22 pairs)
- 2 sex chromosomes (1pair)
24
Q
Internal fertilisation
A
Sperm fertilises egg within female body.
25
Advantages of internal fertilisation
- Fertilisation more likely to occur
- Offspring more likely to survive (protected from predators)
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Disadvantages of internal fertilisation
- Higher energy requirement to care for offspring
- Less offspring produced
27
Oviparous
Internally fertilised egg develops shell. May continue to develop inside female's body or laid in external environment.
28
Viviparous
Internally fertilised egg becomes embryo, and develops inside female's body, obtaining nutrients through placenta.
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Ovo-viviparous
Eggs with yolk for nourishment are retained inside mother's body until ready to hatch, but newly hatched young are born live.
30
External fertilisation
Sperm fertilises egg outside female body.
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Advantages of external fertilisation
- Little energy required to mate
- Large numbers of offspring produced
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Disadvantages of external fertilisation
- Many gametes go unfertilised
- Offspring often not protected
33
Name for female plant reproductive system
Carpel or gynoecium
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Name for male plant reproductive system
Stamen
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Self-pollination
- Transfer of pollen from an anther to a stigma within the same flower or same plant
- Requires less energy
- Plants can grow in areas where animals are absent/few in number
36
Cross-pollination
- Transfer of pollen from an anther of a flower on one plant to a stigma on another plant of the same species.
- Rely on outside agents to transfer pollen.
37
Petals of wind-pollinated flowers
- Small or absent
- Green or dull colour
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Scent of wind-pollinated flowers
Usually none
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Nectar of wind-pollinated flowers
None
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Anthers of wind-pollinated flowers
Protrude outside flower so pollen is easily blown off by wind.
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Stigma of wind-pollinated flowers
- Protrude from flower
- Long/feathery/sticky
- Increased surface area to trap pollen
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Pollen of wind-pollinated flowers
- Small grains
- Light and powdery
- Large amounts produced
43
Petals of bird-pollinated flowers
- Large and colourful (red/orange)
- Tubular shape
44
Scent of bird-pollinated flowers
Rarely fragrant - birds have little sense of smell
45
Nectar of bird-pollinated flowers
Large amounts produced at base of flower
46
Anthers of bird-pollinated flowers
- Lower than stigma
- Colourful
- Sometimes not enclosed by petals
47
Stigma of bird-pollinated flowers
- Higher than anthers
- Colourful
- Sometimes not enclosed by petals
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Pollen of bird-pollinated flowers
- Sticky or powdery
- Small amount produced
49
Petals of insect-pollinated flowers
- Large and colourful (blue/yellow)
- Shaped to encourage pollinators
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Scent of insect-pollinated flowers
Often present - insects highly attracted to scents
51
Nectar of insect-pollinated flowers
Sometimes produced at base of petals
52
Anthers of insect-pollinated flowers
- Enclosed within flower
- Lower than stigma
53
Stigma of insect-pollinated flowers
- Enclosed within flower
- Sticky
- Higher than anthers
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Pollen of insect-pollinated flowers
- Relatively large grains
- Sticky
- Small amount produced
55
Vegetative propagation
New, genetically identical plants arise from portions of an adult plant's roots, stems, leaves or buds.
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Runners (vegetative propagation)
Long, thin modified stems that grow along the surface of soil.
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Rhizomes (vegetative propagation)
Underground, horizontal modified stems that give rise to shoots at each node.
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Suckers (vegetative propagation)
Modified rots that spread quickly and give rise to new plants.
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Apomixis
Some plants produce offspring from generative tissues (gametes or non-reproductive tissue). Gives rise to plantlets that produce asexual seeds.
60
Follicle stimulating hormone (FSH)
- Produced by pituitary gland
- Targets ovaries
- Promotes development of follicle & secretion of oestrogen
61
Luteinising hormone (LH)
- Produced by pituitary gland
- Targets ovaries & testes
- Promotes ovulation, development of corpus luteum & secretion of progestrone in females
- Promotes testosterone secretion in males
62
Prolactin
- Produced by pituitary gland
- Targets mammary glands
- Stimulates milk secretion
63
Oestrogen
- Produced by ovaries
- Targets reproductive tract
- Promotes menstrual cycle & development of female features
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Progestrone
- Produced by ovaries
- Targets uterus
- Prepares uterus & maintains pregnancy
65
Oxytocin
- Produced by posterior pituitary gland
- Targets mammary glands
- Causes release of link, stretches cervix for birth
66
Human chronic gonadotropin (HCG)
- Produced by placenta
- Targets ovaries
- Maintains corpus luteum for production of progestrone
- Stops ovulation
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Testosterone
- Produced by testes
- Targets reproductive tract
- Promotes development of masculine features & behaviours
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Hormones
Chemical substances that coordinate synchronised aspects of body functioning.
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Pituitary gland
Endocrine gland the size of a pea, attached to base of brain above roof of mouth.
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Gametogenesis
Process of gamete production
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Function of ovaries
Produce, store and release eggs into fallopian tubes during ovulation process.
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Function of fallopian tubes
- Connect uterus to ovaries
- Transfer eggs from ovary to uterus
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Function of uterus
- Womb
- Accommodates growing foetus
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Function of cervix
- Connects vagina to uterus
- Expands during childbirth to allow baby to pass through
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Function of vagina
- Pathway (birth canal) through which baby leaves woman's body
- Can expand and contract to accommodate baby
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Function of testes
Make and store sperm cells
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Function of vas deferens
- Sperm duct
- Contains sperm cells
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Function of epididymis
Transports sperm
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Function of seminal vesicle and prostate gland
- Accessory glands
- Provide fluids to duct system
- Contribute to sperm transport
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Function of scrotum
- Sac of skin containing testes
- Regulates and ensures correct temp. for sperm production
81
Haploid (n)
Cells that only have one set of chromosomes (one copy of each chromosome)
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Diploid (2n)
Cells that have two sets of chromosomes (one paternal, one maternal)
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DNA
- Deoxyribonucleic acid
- Molecule which carries genetic information
- Double helix shape
- Long chain of nucleotides
84
Nucleotide structure
- Sugar
- Phosphate
- Nitrogenous base (A, T, G or C)
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Genome
- An organism's complete set of DNA
- All information needed to grow & survive
86
Gene
- Section of DNA
- Each codes for different characteristics
- Template for mRNA strand that is translated into polypeptide
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Alleles
- Alternative forms of the same gene
- Found at same place on same chromosome in same-species organisms
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Genotype
An organism's genetic makeup, or type of genes, for a particular characteristic.
89
Phenotype
An organism's observable physical expression of a characteristic/gene. Determined by genes present and environmental factors.
90
Autosomal dominant trait
- Affected individual always has at least 1 affected parent
- 2 affected parents can have unaffected child
91
Autosomal recessive trait
- Affected individual may have unaffected parents
- 2 affected parents only have affected children
92
X chromosome recessive (sex-linked) trait
- Occurs more often in males
- Male inheritance can skip a generation
- All sons of affected female are also affected
93
Homozygous (RR or rr)
Refers to individuals carrying two identical alleles.
94
Heterozygous (Rr)
Refers to individuals carrying two different alleles.
95
Codominance
No recessive alleles for a trait, therefore both alleles are expressed at the same time without blending of the trait. E.g. spotted/patched fur
96
Incomplete dominance
Neither allele is expressed fully, resulting in a third phenotype with blended characteristics.
97
Female sex chromosomes
XX
98
Male sex chromosomes
XY
99
Sex chromosomes
Code for sexual characteristics and determing sex of an organism, however also contain genes that code for non-sex-specific characteristics.
100
Autosomes
Chromosomes that do not code for sex-specific characteristics.
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Transcription (polypeptide synthesis)
- RNA polymerase binds to DNA & unzips it
- Information copied to mRNA
- Thymine replaced with Uracil
- mRNA moves into cytoplasm
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Translation (polypeptide synthesis)
- mRNA translates into series of amino acids based on codons
- tRNA anti-codon matches corresponding codon to deliver correct amino acid.
- Peptide bonds link amino acids, forming polypeptides
104
RNA
- Ribonucleic acid
- Single-stranded
- 4 nitrogenous bases - A, U, G, C
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mRNA
- Messenger RNA
- Intermediate molecule - carries info from DNA in nucleus to ribosomes in cytoplasm
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tRNA
- Transfer RNA
- In cytoplasm
- One end (anticodon) binds with mRNA codon, other end binds to 1 specific amino acid.
108
rRNA
- Forms ribosome structure
- Made in cell nucleolus
108
Gene expression
Translation of genes into protein end products
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What two factors affect gene expression/phenotype? (hint: nature vs nurture)
- Nature of genotype
- Environmental factors (nurture)
110
Epigenetics
Modern research into how environment influences gene expression at a molecular level. Revealed that environment chemically modifies DNA without changing base sequence - by adding chemical markers/tags.
111
Which 5 elements combine to form amino acids? (hint: CHONS)
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
- Sulfur
112
How many different amino acids?
20
113
Primary protein structure
Amino acids arranged in linear chains/polypeptides
114
Secondary protein structure
- 3D arrangement of polypeptide chain
- Amino acid chains linked by H2 bonds
- Forms spiral (alpha helix) or pleated sheet
115
Tertiary protein structure
Complex 3D shape due to forces of attraction between alpha helices & pleated sheets.
116
Quaternary protein structure
Multiple proteins link to create more complex 3D structure
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Fibrous proteins
- Form structural components of cells & tissues
- Long, insoluble in water
118
Globular proteins
- Often used as transport proteins
- Spherical, compact, soluble in water
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Structural proteins
- Provide cell shape, support, movement
- Fibrous & stringy
- Form cytoskeleton
120
Enzymes
- Control biochemical reactions and cellular metabolism
- Catalyse reactions
121
Communication proteins
Help cells communicate using chemical signals and biological recognition
122
Transport & storage proteins
Bind to & carry/store chemicals
123
Sensory proteins
Change shape or biochemical activity in response to stimuli
