Genetics and the reproductive system Flashcards
What is asexual?
- one parent
- its young are identical copies of itself
- E.g. bacteria, plant runners and cuttings
What is sexual?
- two parents
- each parents has sex organs: GAMETES
- female gametes: eggs or ova
- Male gametes: sperm
Describe the human life cycle:
- Adults produce gametes by meiosis
- Each gamete contains only one-half the number of chromosomes
Describe the two types of chromosomes:
- cells, containing 46 chromosomes, are called DIPLOID CELLS, and are abbreviated as “2n”
- The gametes, containing 23 chromosomes, are called HAPLOID CELLS, and are abbreviated as “n”.
How does fertilisation work?
- A haploid ovum and a haploid sperm unite through fertilisation
- A diploid zygote is produced
- Down syndrome child has an extra chromosome
What does fertilisation describe?
This life cycle describes how diploid (2n) adults produce haploid (n) gametes, which then unite to form a new diploid (2n) zygote.
Facts puberty/hormone/gamete male:
PUBERTY: voice deepens, body becomes more muscular, body and facial hair grows, the testes and penis grow larger, testes begin producing sperm.
HORMONE: testosterone
GAMETE: sperm
Facts puberty/hormone/ gamete female:
PUBERTY: breasts develop, hips grow and become rounder, body hair begins to grow, vagina and uterus becomes larger, menstrual periods start.
HORMONE: oestrogen
GEMETE: eggs
What is meiosis?
The cell division to form two cells with only 23 chromosomes in each sex cell.
This occurs only in sex organs to form gametes.
what are the changes to a males body during puberty caused by?
Testosterone produced in the testes.
What is the male sec cell and where is it stored?
Sperm, produced in the testes and stored in the EPIDIDYMIS.
Where is the testes stored?
a sac of skin known as the scrotum
In what glands produce the liquid part of sperm?
- Prostate gland
- Seminal vesicles
- Cowpers glands.
What is semen?
The sperm swimming in fluid produced by the prostate gland and seminal vesicles.
What do the testes do?
Make sperm and hormone testosterone
What does the penis do?
Passes sperm from body into woman’s body during intercourse
What is the vas deferens purpose?
Sperm go through was deferens from testis to the penis.
What indicates the beginning of sexual maturity in females?
The ovaries start to produce mature ova. This is caused by the hormone OESTROGEN.
Ovaries?
Contain developing ova
Fallopian tubes?
Ovum moves down these tubes ti uterus/womb.
Uterus?
a big bag in which a fertilised ovum develops into a baby.
Cervix?
A ring of muscle that close the lower part of the uterus
Vagina?
Tube that leads to uterus
Vulva?
Outer opening of vagina
What are the two possibilities for the menstrual cycle?
NO FUSION of ovum with sperm. 14 days after ovulation, the lining of the uterus wall will be shed-MENSTRUATION.
FUSION of the ovum and sperm in the oviduct- FERTILISATION
When is the fertile time?
Between day 9 and 15
Describe chromosomes:
threadlike structures made of DNA and are found in the nucleus of cells
What is a Karyotype?
A pair of chromosomes
What does DNA stand for?
Deoxyribonucleic Acid
What is in each chromosome?
A double-helix DNA molecule
Define gene:
A length of DNA containing a small part of genetic code. A chromosome contains more than 1000 genes.
What do DNA bases do?
The order of the bases making up the DNA of a chromosome carry encoded messages that determine the characteristics of an organism.
What are the stages of mitosis?
PROPHASE > METAPHASE > ANAPHASE > TELOPHASE
What are the stages of meiosis?
PARENT CELLS > DNA REPLICATES > TWO DAUGHTER CELLS > FOUR DAUGHTER CELLS.
What is a zygote?
The chromosome of 23 pairs which exists after the fusion of egg and sperm.
Define dominant?
Will occur over a recessive characteristic.
What is an allele?
The different forms of the gene.
Homozygous or homologous?
identical alleles
Heterozygous?
Combination alleles
Incomplete dominance?
Some genes do not have dominant and recessive alleles, this results in a “blending” of the two alleles.
Co-dominance?
Some cases where both alleles in the heterozygous offspring are expressed in the phenotype.
Explain sex linkage:
There are some genes which are only found on one chromosome, usually the X.
What are chromosomes that are not sex ones called (just in your normal cells)?
Autosomes
Explain chromosomal abnormalities:
- Sometimes during meiosis, DNA information passed on to the next generation is changed.
- If the DNA is not copied exactly, this type of change is called a MUTATION.
e. g. Cystic Fibrosis, Muscular Dystrophy
Explain inherited characteristics?
Eye colour, nose shape, hair type and skin colour are characteristics you can inherit from parents.
What acquired characteristic?
know how to swim, speak french and cars from cars.
What is natural selection?
- Organisms are well adapted to their environment
- They posess structural, functional and behavioral characteristics that made them able to survive and reproduce in that environment.
- Offspring will show variation and sometimes mutations
- Some mutations will improve the chances of survival
What is evidence of evolution?
FOSSILS-evidence over 10 000 years old
Divergent evolution?
organisms becoming LESS alike due to different habitats.
Convergent evolution?
Organisms becoming MORE alike due to simliar environments
Parallel evolution?
Species evolving similar features independently in different areas, e.g. crocodile and aligator
Analogous structures?
- Structures which serve the same function and often the same appearance but have different origins.
e. g. the human and octopus eye are similar but they have developed independently.
comparative anatomy?
The limbs of reptiles, bird, amphibians and mammals have similar structural features
Comparative embryology?
Similar features in many related species.
e.g. Gill slits, tail, dorsal brain and spinal cord.
These develop before more specialised structures.
Vestigal structures?
Reduced structures.
e.g. wings into Drosophila, appendix and coccygeal vertebrae of humans.
Horse evolution?
Stages in horse evolution showing the reduction in the number of toes and foot bones.
Intermediate forms?
Suggest a continuum at development.
e.g. dinosaurs, archaeopteryx.
What was the land mass of all continents originally called?
Pangea
What is biogreography?
study of fossils and living organisms reveal patterms which suggest relationships between species in Australia, South Africa, New Zealand ect.
The theory of Evolution?
The process by which organisms best suited to their environment survive to pass their genes on to their offspring in increasing numbers, in contrast to the less well-adapted organisms in the population who produce fewer organisms or do not breed at all.
Complete the stages of the human life cycle:
Adult male, diploid 2n=46 + Adult female, diploid 2n=46 go through meiosis. Ovum and Sperm (haploid, n=23) go through fertilisation and form a zygote (diploid, 2n=46). Mitosis now occurs and the zygote becomes the embryo, which after week 8 is called a foetus.
What do the following things mean in DNA: D P A T G C
D=Deoxyribose sugar P=Phosphate A=Adenine T=Thymine G=Guanine C=Cytosine
Chromosome?
A densely coiled structure that holds the DNA ready for cell division.
Gene?
A section of the genome that provides the code for a particular protein/characteristic
Dominant?
A trait that masks the other trait of a pair, if present.
Recessive?
A trait that is only visible of no dominant trait is present.
Alleles?
An alternative form of a particular gene.
Falopian tube?
Ovum moves down these tubes to uterus/womb.
Ovary?
Contain developing ova
Vagina?
Tube that leads to uterus
Vulva?
Outer opening of vagina
Bladder?
Stores urine
Pubic bone?
Forms the front arch of the pelvis
Erectile tissue?
Spongy tissue that expands and becomes hard when filled with blood.
Fossil record?
fossils are any evidence of an organism from a former geological time. Fossil record is the history of life on Earth as recorded by these fossils.
DNA Hybridization?
A technique for combining single DNA strands from twos specie, to compare their similarity.
placenta?
Organ in the uterus which nourishes the foetus through the umbilical cord.
