Cells and control UP TO 2.13 (adaptations of neurones heading in notes)

stages of the cell cycle

interphase, mitosis cytokinesis

stages of mitosis

prophase

metaphase

anaphase

telophase

stages of mitosis acronym

PMAT

interphase

the cells spends most of it's life in this phase

the DNA in chromosomes copies itself ready for mitosis

prophase

- nuclear membrane disappears

- the DNA unwinds and condenses into chromosomes

- spindle fibres become visible

metaphase

- chromosomes line up along the centre of the cell

- spindle fibres attach to the chromosomes

anaphase

- chromatids are pulled to the edges of the cell

- by the spindle fibres

telophase

- nuclear membrane forms around each of the sets of chromosomes at each end of the cell

- separating them from one another

cytokinesis

splits the cytoplasm to create 2 identical diploid daughter cells

what is mitosis required for?

growth

repair

asexual reproduction

role of mitosis in growth

mitosis produces new cells

role of mitosis in repair

to replace damaged or dead cells

role of mitosis in asexual reproduction

mitosis produces offspring that are genetically identical to the parent

describe mitosis

division of a cell by mitosis results in:

- the production of 2 daughter cells

- each with identical sets of chromosomes in the nucleus to the parent cell

- resulting in the formation of two genetically identical diploid daughter cells

cancer

- cancer is the result of mutations in the DNA

- where cell division is rapid and uncontrolled

- resulting in the formation of a tumour

through what processes do animals grow?

cell division (mitosis + meiosis)

cell differentiation

through what processes do plants grow?

cell division (mitosis + meiosis)

cell differentiation

cell elongation

cell differentiation

where a cell becomes specialized for a specific structure or function.

cell elongation in plants

where hormones, such as auxin, cause cells to grow longer in response to certain stimuli e.g. sunlight

importance of cell differentiation

Differentiated cells are important in a multicellular organism because they are able to perform vital specialised functions in the body. (eg. sperm)

cell differentiation in animals

in an animal, most cells differentiate at an early stage of it's development, with mature animals mainly restricted to repair and replacement of cells, not growth

the only cells able to differentiate throughout the life of an animal are adult stem cells

cell differentiation in plants

unlike animals, plant cells can fully differentiate throughout the plant's life, not just in the early stages of development

why are growth charts used?

to monitor the growth of an organism by comparing it's growth to the usual trends for that particular organism

how to read a growth curve

- find your child's weight and height and find where they intersect

- if a baby is on the 25th percentile, it means that they are lighter than 75% of babies their age, and heavier than 25% of babies their age

when is growth abnormal?

if someone moves from e.g. The 5th to 70th percentile in a short space of time

embryonic stem cells

- an undifferentiated stem cell

- form when an egg and sperm cell fuse to form a zygote

- can differentiate into any type of cell in the body

how can embryonic stem cells be used in medicine?

because they are undifferentiated, they can be stimulated to produce any type of cell

they can:

- repair damaged tissue

- replace damaged cells

in order to treat a variety of diseases e.g. Parkinson's, and replace damaged tissue e.g. nerve cells.

how can adult stem cells be used?

if found in bone marrow, adult stem cells can be used to form some types of cell including blood cells

stem cells in plants

found in meristems

can be used to make clones of teh plant, may be useful if the parent plant has certain desirable characteristics e.g. disease resistance

benefits of embryonic stem cells in medicine

- can be differentiated into any type of cell

- can be used to replace damaged cells or repair damaged tissue to treat/reduce symptoms of diseases e.g. arthritis

risks of using embryonic stem cells in medicine

- stem cells continue to divide and could cause cancer

- cells could be rejected

- removal of stem cells kills the embryo= ethical objections

cerebellum location

back of brain

cerebellum function

controls balance, movement and fine motor skills

medulla oblongata location

medulla oblongata function

connects brain to rest of nervous system

controls unconcious activities e.g. heart rate, breathing etc

cerebral cortex location

cerebral cortex function

split into 2 hemispheres- left hemisphere communicates with right side of body and vice versa

controls language, memory, emotion and behaviour

2 types of scan we can use on the brain

CT

PET

why do we use CT and PET scans

the brain is very delicate so surgery is very risky

scanners mean that we can investigate brain function without resorting to surgury

CT scans

Multiple X-Rays of successive slices of the brain.

Show brain structure.

PET scans

Show areas of brain activity

Patient is injected with radioactive glucose. the areas that use up more glucose are the ones with the most activity because the cells are respiring. These areas become radioactive so can be spotted

This is why PET scans are often used to detect cancer

limitations in treating brain tumours

surgery to cut out the tumour is difficult because:

- the brain is protected by the skull so difficult to access

- there is a significant risk of damage to the brain

limitations in treating spinal cord injuries

damaged neurones cannot be repaired or replaced by the body

but stem cell injections are getting developed

what is the central nervous system (CNS)?

brain and spinal cord

neurone definition

specialised cells adapted to rapidly carry electrical charges (nerve impulses) from one part of hte body to another

a bundle of neurones= a nerve

what are the 3 types of neurone?

sensory

relay

motor

role of sensory neurones

carry impulses from sense organs to CNS (brain/spinal cord)

role of relay neurones

in the CNS

connect the sensory + motor neurones

role of motor neurones

carry impulses from CNS to effectors (muscles or glands)