Biology Fertilization Genetics etc.

Exam 2

What happens during catabolic reactions? What happens after?

Large molecules are broken down into small ones
Energy is released

What happens during anabolic reactions?

Small molecules are assembled into large ones
Energy is required

Definition active site

A region on an enzyme where the substrate binds

What is an “induced-fit”?

Active sites mold around the substrate = more efficient

Denaturing of enzymes (3)

Enzyme active site mutation = food doesn’t break down
Abnormal pH level: Enzyme’s shape depends on the pH (acidity of environment)
Low enzyme production = low reaction rate

What happens at the end of Meiosis I?

Chromosomes are separated

Name all the steps of Meiosis I

Prophase I
Metaphase I
Anaphase I
Telophase I

What happens during Prophase I ?

chromosomes condense
crossing over
nuclear envelope breaks down, spindle forms

What happens during Metaphase I ?

chromosome pairs align at the cell’s equator
random arrangement

What happens during Anaphase I

chromosomes are pulled apart (poles)
sister chrmoatids stay together

Telophase I

two nuclei form
cell splits into 2 haploid cells
each chromosome still has two sister chromatids

What happens at the end of Meiosis II ?

Sister chromatids are separated

What happens during Prophase II

chromosomes condense again
spindles form

Metaphase II

chromosomes line up at equator

Anaphase II

sister chromatids are pulled apart

Telophase II

nuclear envelope forms
cell divides again = 4 haploid daughter cells

What is the role of meiosis in the sexual life cycle ? (3)

maintain chromosomes number
genetic variation
foundation of fertilization

Why do enzymes denature due to temp. or other effects?

Enzyme active site mutation: food doesn’t break down
Abnormal pH: Enzyme’s shape depends on the pH (acidity) of environment
Low enzyme production: low reaction rate

What is random orientation ?

metaphase I: alignment is purely by chance
n pairs of chromosomes = 2^n different reproductive cells

What is recombination (crossing over) ?

prophase I: exchange of genetic material between non-sister chromatids

What is the outcome of asexual reproduction ?

organisms that are adapted also produce offspring that are adapted

What are new gene combinations and genetic variations of asexual reproduction ?

gene combinations are maintained
no variation (except mutations)

Genetic variability of asexual reproduction ?

offspring are genetically identical

cellular processes in mitosis / meiosis with asexual reproduction

mitosis is used throughout asexual cycle

number of parents in asexual reproduction

1

number of parents in sexual reproduction

2

cellular processes meiosis / mitosis in sexual reproduction

meiosis used once per generation in a sexual life cycle

Genetic variability of sexual reproduction

offspring are genetically different

What are gene combinations and genetic variation in sexual reproduction ?

new gene combinations produced in each generation
genetic variation is generated (+ mutations)

What is the outcome of sexual reproduction ?

offspring are better adapted than their parents (if environment changes)

What is the difference between Motility in male and female gametes?

Male: travel to female
Female: are sessile (in reproductive system)

What is the difference in size between male and female gametes

Male: Smaller
Female: Larger

What is the difference between male and female gametes in food reserves ?

Male: Less because only enough for the gamete to travel to the egg cell
Female: more because enough for development of an embryo

What is the difference between male and female gametes in numbers produced

Male: very large numbers
Female: sometimes only one

What are the different phases of the menstrual cycle ?

Menstrual phase 1-5
Follicular phase 1-13
Ovulation 14
Luteal phase 15-28

What happens during the Menstrual phase ?

6-12 oocytes mature/develop
uterine lining is shed

What happens during the Follicular phase ?

Proliferation = thicker uterine lining
FSH and LH start to rise = stimulations of ovarian follicles = secretion of oestrogen
Oestrogen inhibits additional FSH and LH = drop
around day 12: no negative feedback but positive on pituairy glands = spike in FSH and LH

What happens during ovulation ?

peak LH (+ oestrogen) triggers ovulation

What happens in the luteal phase ?

LH differentiates follicle cells into corpus luteum
secreting oestrogen and progesterone = inhibition of FSH and LH
LH is required to maintain life for embryo
If no embryo = degeneration = no more oestrogen and progesterone = uterine lining breaks down

What is a step by step of Fertilization ?

Ejaculation
Initial sperm loss
Entry into the fallopian tubes (100-1000)
chemotaxis and sperm navigation
reaching the egg
membrane fusion
cortical reaction
sperm components fate
zygote formation