DEVELOPMENTAL BIOLOGY Flashcards Preview

eBMS2011 > DEVELOPMENTAL BIOLOGY > Flashcards

Flashcards in DEVELOPMENTAL BIOLOGY Deck (21)
Loading flashcards...
1

What are the cyclical phases of human development

Reproduction
Fertilisation
Cleavage
Gastrulation
Neurulation
Organogenesis
Growth and maturation
Puberty
Reproduction

2

What can the first trimester be called

the embryonic period

after this it becomes the foetal period

3

How does a pregnancy test work

Human chorionic gonadotrophin (hCG) hormone is secreted by the placenta after embryo implantation (day 7-8)

Detected in blood and urine

4

What is an ectopic pregnancy

Where implantation does not occur in the uterus, but outside of the uterus.

90% are tubal causing bleeding and tubal miscarriage

5

What is hydatidiform mole

only the trophoblast proliferates and not the ICM. No embryo develops

hCG still secreted giving +ve on test, needs ultrasound to confirm

Symptoms: abnormal growth and vaginal bleeding

6

Outline neural crest cells

Cells derived from junction of neural plate and epidermis. Undergo EMT and migrate down tracks due to growth factors.

Gives rise to:
- craniofacial region (cartilage and bone)
- odontoblasts (dentine of teeth)
- melanocytes
- heart
- brachial arch derivatives (throat)
- PNS

7

What specific structures do neural crest cells give rise to

Cranial: bone and cartilage of face/neck, cranial nerves, bones of ear and jaw

Cardiac: outflow tract of heart, neurons

Trunk: sympathetic neutrons of dorsal root ganglia (sensory), melanocytes of dermis

Sacral: parasympathetic nerves (enteric ganglia) of gut

8

What is a neural tube defect and what are 2 forms

Failure of neural tube closure in first trimester

Anencephaly: cephalic part of neural tube fails to close, absence of major portion of brain (deaf, blind, unconscious)

Spina bifida: posterior neural tube fails to close, vertebrae remain open, spinal cord exposed, neural disability (risk reduced by folic acid)

9

Outline cardiogenesis

Development of the heart.

Two tubes fuse at the midline and fold to form the heart. Tubes also contribute to blood vessel formation

10

What is a congenital birth defect

Abnormalities of development present at or before birth.

first trimester is most sensitive

nervous system is most sensitive to issues over whole process of development

2 types: genetic or environmental (from teratogens)

11

Example of a single gene defect

Duchenne muscular dystrophy: muscle degradation

x linked recessive disorder

Mutation of dystrophin gene which encodes for dystrophin

Dystrophin connects cytoskeleton of muscle fibre cells to the surrounding ECM

12

What is a syndrome

A variety of different effects due to several genes being affected.

13

What are imprinting genes

Differences in activation of genes depending on the parental origin of the chromosome

e.g. one gene may be off in father and on in mother. If mothers then is mutated then both genes will be off and there will be no gene working

14

What is a chromosomal defect

Larger scale and cause a loss or gain of DNA. Genes are unaltered but a chromosome is duplicated or deleted

e.g. trisomy 21 = down syndrome

15

Outline the human cerebral cortex

much more folded so more neurons and connections between regions

high development in parts for sensory perception, conscious thought, language, abstraction and problem solving

16

Outline the human neocortex

human brain maintains its foetal growth rate.

highly plastic, constantly changing and remodelling.

high levels of gene transcription

17

Explain how gene regulation effects brain growth

changes in gene regulation can account for massive human brain growth.

Changes in non coding DNA, non coding RNAs and gene regulatory regions

18

Explain what HARs are

human accelerated regions are rapidly evolving regulatory elements, often located near brain expressed genes.

Preserved through vertebrates but extremely different in humans.

Therefore could be a reason for human development

19

Explain how unique human traits can be related to DNA loss

removal of regulator of growth suppressor GADD45G results in loss of its expression which may be linked to increased brain growth in humans

20

What are some human characteristics of Neoteny

little body hair
small jaws
lengthened period of youth
growth and development of the skull.

Gene transcriptional neoteny occurs in the frontal cortex of the brain

21

Explain neoteny in the frontal cortex

Gene transcriptional neoteny occurs in the frontal cortex of the brain

embryonic expressed genes still expressed at post natal stages