Science 9 - Biology Unit Test Flashcards
infertility
inability of couple to have baby; might be because…
- male not producing enough sperm
- male producing deformed/defective sperm
- female unable to release eggs (not enough of right kind of hormones)
- medical procedures (chemotherapy or radiation therapy)
cri-du-chat syndrome
also known as crying cat syndrome
- 1 in 50 000 individuals
- caused by deletion on short arm of chromosome 5
- usually small at birth
- respiratory problems
- larynx (voice box) doesn’t develop correctly (causes cat-like cry)
- small head, small chin
- unusually round face, widely set eyes
fetal development
- three layers of gastrula form tissue & organs of a baby
- takes 38 weeks & divided into three trimesters (three months long)
- at end of 8 weeks, embryo called fetus
blastula
- end of second week
- embryo 1.5mm in diameter and has hollow ball of cells
- cells now embryonic stem cells
Turner syndrome
- 1 in 5000 females
- only 1 ‘x’ chromosome instead of 2
- female sexual characteristics underdeveloped
- short stature
- swelling of hands and feet
- low hairline, low-set ears
- reproductive sterility, absence of menstrual period
- increased weight –> obesity
homologous chromosomes
a pair of matching chromosomes (one from each parent)
when do chromosome mutations occur?
during meiosis
when is oocyte cryopreservation used?
- women diagnosed with cancer who have not begun chemotherapy or radiation therapy
- women undergoing assisted reproductive technologies who do not consider embryo-freezing an option
- women who want to preserve future ability to have children, because they do not yet have a partner, or for other personal or medical reasons
mating
process by which both gametes (sex cells) arrive at the same place at the same time
haploid number
(n)
one set
pair of chromosomes
what do karyotypes show?
when whole chromosome mutations have occurred
- can be analyzed to diagnose and treat patients with genetic disorders or syndromes
result of whole chromosome mutations in meiosis 1 & 2
1 gamete will have 2 copies of 1 chromosome, and another will have none
ectoderm
- outer layer
- cells form skin and nervous system
embryonic development
- early development of organisms
- takes place in humans during first 2 months (8 weeks) after fertilization
impact reproductive technologies in society
- IVF causes higher chance of birth defect
- most unused embryos donated to stem cell research
- with AI, most children never know who biological father is
- in surrogacy, sometimes arguments over custody of child
hormone therapy
might cause female to ovulate
third trimester
continued growth
- rapid weigh gain; growth and accumulation of fat (26-38 weeks) {40-50 weeks}
three layers of cells that organize during gastrula
- ectoderm
- mesoderm
- endoderm
which has a greater impact; chromosome or gene mutations
chromosomes mutations because bigger DNA sequences are changed
independent assortment (during meiosis 1)
- homologous pairs of chromosomes separate at equator, move towards opposite poles of the cell
- many different possibilities for how they will separate produces variation –> there are over 8 million sperm combinations possible for the 23 pairs in an egg or sperm cell!
females (gamete formation)
meiosis 1 - produces 2 egg cells (cytoplasm & organelles are not equally divided)
meiosis 2 - produces 4 cells —> three smallest disintegrate –> one large haploid egg cell
result of meiosis? (gametes)
four haploid cells, each with half the number of chromosomes
advantages of external fertilization
- little energy required
- large number offspring produced at once
- offspring far from parents (less competition and genetic variation maintained)
crossing over during meiosis 1
- parts of non-sister chromatids “cross over” each other and exchange segments of DNA
- this produces genetic variation
gene mutation
change in specific order of A, G, C, and T bases that make up a particular gene
difference between meiosis 1 and 2?
meiosis 1:
- homologous chromosomes line up at the equator, then separate and move to opposite poles of the cell
meiosis 2:
- chromatids of each chromosome are pulled to opposite poles
Down syndrome
- 1 in 1000 individuals
- extra 21st (trisomy 21)
- mild to moderate learning disabilities
- almond shape to the eyes
- shorter limbs, pore muscle tone
- larger than normal space between big and 2nd toe
- protruding tongue
what happens during fertilization?
2 gametes (n) fuse to form a zygote (2n)
in vitro fertilization
- used when female Fallopian tubes are blocked (tube connects ovaries to uterus)
- egg cells removed from ovaries and placed in Petri dish, fertilized eggs implanted into uterus few days after fertilization
- more than one egg used, multiple births common
surrogacy
couple asks surrogate mother to carry embryo provided by couple, sometimes surrogate mother asked to produce egg
intracytoplasmic sperm injection
- only one sperm cell in egg cell, zygote later inserted in female’s uterus
- only 25% of ICSI procedures result in birth
advantages internal fertilization
- embryo protected (inside female) & parents care for young –> more offspring survive
mesoderm
- middle layer
- cells form kidneys, muscles, blood vessels, reproductive organs, bones
where does the genetic information in the zygote come from?
half from one parent, half from the other
n + n = 2n
artificial insemination
- sperm collected and injected into female
- widely used to breed farm animals
- in humans, sometimes sperm collected from female’s partner and injected into female. sometimes, if male unable to produce enough viable sperm, sperm donor (usually anonymous) is used
how DNA can be affected
- lost
- duplicated
- inverted (flipped)
- moved within a chromosome
- moved to another chromosome
how can pollen be transported?
- colourful flowers attract pollinators which spread pollen as they take nectar from flowers
- by the wind
- for plants without flowers: pollen transported by wind from male cones to female cones
pollination
- form of internal fertilization used by plants
- transfer of male gametes in pollen from male reproductive part to female reproductive part
- pollen tube forms to deliver sperm cells to egg cells once pollen lands on female part of plant (pistil)
- after fertilization zygote grows into embryo, nourished by food within seed in which it grows (seed protects embryo)
assisted reproductive corrective technology procedures
- hormone therapy
- artificial insemination (AI)
- in vitro fertilization (IVF) {test tube baby}
- gametes intrafallopian transfer (GIFT)
- intracytoplasmic sperm injection (ICSI)
- oocyte cryopreservation
gametes
specialized cells necessary for reproduction
ex; eggs, sperm, pollen
why don’t large chromosome mutations usually pass down to new generations?
offspring doesn’t develop, doesn’t succeed, doesn’t reach reproductive age, or is infertile
first trimester
developing organ systems
- brain, spinal cord forming (3 weeks) {4 mm}
- digits, ears, organs, and muscles forming (6 weeks) {4 cm}
- sexual differentiation (9 weeks) {9 cm}
what does sexual reproduction require?
two parents
what does haploid vs. diploid refer to?
the number of chromosomes
second trimester
growth
- fetal movements felt (16-18 weeks) {20 cm}
- eyelids open, fetus can survive with special care if born now (24 weeks) {35 cm}
males (gamete formation)
meiosis 1 - produces 2 cells
meiosis 2 - produces 4 cells with cytoplasm & organelles equally divided (4 haploid sperm cells
how are chromosome mutations caused?
by mutagens
endoderm
- inner layer
- cells form lungs, lining of digestive system
stages of sexual reproduction
- mating (ritual)
- fertilization (external or internal)
- development
morula
- end of first week
- embryo is 0.2mm in diameter
who are offspring genetically different from?
in sexual reproduction
- each other
- either parent
- any other member of their species