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nuclear DNA
all living things use same DNA code
seq of bases varies
species more distantly related, more diffs in seq
species closely relates, less diffs in seq
DNA sequencing
The determination of the precise order of nucleotides in a sample of DNA
introns
non coding seqs of DNS that have no apparent function + seem to serve no purpose
e.g endogenous retroviruses
more closely related species, have more introns in common
endogenous retroviruses
a viral sequence that has become part of an organism’s DNA
store genetic info as RNA
RNA genome copied into DNA when it enters a cell in reverse transcription
DNA becomes inserted into one host cells chromosome + passed to next gen
mitochondrial DNA
small, circular molecules
inherited only from mum
mtDNA comparisons uses to compare organisms w/in a species or closely related species
closely related may share identical mtDNA
if very diff, last common maternal ancestor lived long ago
autonomy as an ethical consideration for genetic info
respect for the right to be self-determining + to choose whether or not to be tested and, if tested, to know + share the info. It also includes the right of an individual to decide their own future, independent of genetic info
confidentiality as an ethical consideration for genetic info
the use of genetic information is treated sensitively, + is accessed only by those who are authorised.
equity as an ethical consideration for genetic info
the right to fair + equal treatment regardless of genetic information.
privacy as an ethical consideration for genetic info
the right to be ‘left alone’ + to make decisions regarding genetic testing + the resulting information, independent of others
comparative protein studies
comparison of types + seqs of A.A making up a protein
longer the period of time, greater the no. of A.A that would be diff
animals of same species have identical A.A seq
ubiquitous proteins
one of a group of proteins that appears to be in all species from bacteria to humans e.g cytochrome C
cytochome C
has changed v little over millions of years
104 A.A in humans
37 of the A.A in cytochrome C found in same spot of every sequenced cytochrome C, regardless of species
more similar the A.A seq, more recently they evolved from a C.A
bioinformatics
use of computers to describe the molecular components of living things
it is a multidisciplinary field
uses biochemical analysis to gain info abt DNA + proteins + computer software to store + analyse it
multidisciplinary field
combines all areas of biological science w/ computer science, engineering, statistics + applied mathematics to help understand biological processes
what is bioinformatics used for
Useful in tracing the evolution of a large no. of organisms by measuring changes in their DNA
more similar the genes, more closely related
can compare entire genomes
how are genes in a DNA seq identified in bioinformatics
through a process called annotation which needs to be computerised as more genomes are too large to be annotated by hand
fossil
any preserved trace left by an organism that lived long ago e.g bones, teeth
what can fossils show
how species evolved + determine relatedness
what conditions are required to create a fossil
soil w/ no oxygen, as oxygen allows preservation
alkaline soil, as it allows minerals in bones to not be dissolved
rapid burial that prevents decomposition + no invasion from micro organisms
hard body parts
examples of places where fossilisation can occur
being buried by drifting sand, mud deposited by rivers + volcanic ash
if a cave wall containing limestone collapses and covers bodies of animals
problems w/ the fossil record
incomplete due to specific conditions needed for fossilisation
fossils may not have formed + most fossils are undiscovered
dating fossils is challenging; carbon dating only accurate up to 60000 years + other methods require specific surrounding conditions
fossils finds often incomplete which requires reconstruction + fragments are subject to interpretation
relative dating
determining the age of a fossil or artefact in comparison to smth else
stratigraphy
the study of layers/strata of rock
principle of superposition
layers at the top of sedimentary rock are younger than those beneath them
correlation of rock strata
the process of matching layers of rock from diff locations
movement of earth’s crust makes this difficult
index fossils
fossils of organisms that were widely distributed + were present on earth for only a limited period of time
will only be found in 1 rock strata
these fossils are used to correlate strata
absolute dating
determining the actual age of the specimen years
isotope
atoms w/ the same no. of proteins but diff no. of neutrons
radioactive isotopes
atoms that contain an unstable combo of neutrons + protons or excess energy in their nucleus
radioactive decay
atoms w/ an unstable nucleus regain stability by excess particles + energy in the form of radiation
half life
the time required for half of the radioactive material to decay into stable non radioactive material
potassium argon dating
K-ar dating is based on the decay of potassium 40 to form calcium + argon 40
slow but steady decay
half life = 1.25 billion years
limitations of potassium argon dating
can only date volcanic rock or rock that contains potassium
can only date volcanic rocks older than 200000 years
carbon 14 dating
the decay of carbon 14 to nitrogen 14
half life is 5730 ± 40 years
ratio of C14 to C12 can be estimated + the age of the sample can be calculated
limitations of carbon 14 dating
normal method requires at least 3g of organic material (AMS radiocarbon dating has enabled samples as small as 100 micrograms)
cannot be used to date back more than 60000 years
must contain organic compounds
ratio of C14 to C12 in atmosphere was thought to be constant but we now know amount of C14 in atmosphere varies
phylogenetic tree
a diagram showing evolutionary relationships between related organisms
characteristics of phylogenetic tree
ancestral organism = base of the tree
organisms derived from ancestor = branches
closer related = branches close to one another
what are phylogenetic trees useful for
representing relationships as well as organising knowledge of genetic diversity + structural classifications
what order are humans
primates
what family are humans
hominid
what tribe are humans
hominin
what genus are humans
homo
what species are humans
sapiens
characteristics of primates
pentadactyl
nails
grasping fingers + toes, w/ friction ridges for gripping
opposable thumb
forward facing 3D vision
most able to distinguish colour
very poor sense of smell
4 incisors in lower + upper jaw
large + complex brain
cerebrum size inc as primates evolve more
rhythmical sexual cycle
long period of parental care
usually one offspring at a time
why was there a change from quadrupedalism to bipedalism
climate become cooler + dryer
trees became widely separated
had to leave the trees and move across great grasslands to seek out resources
how has the foramen magnum evolved
from apes to humans it has moved forward to become more central
this allows skull to balance on top of vertebral column
apes used large neck muscles to hold brain in place, but we use vertebral column, so it needed to become more central
how has the curvature of spinal column evolved
apes had a C shaped curve
now we have a S shaped curve
the lumbar have become wedge shaped to allow the S shape
this allows an upright position + head to balance on top of neck
evolution of the jaw
apes had a prognathic jaw
humans have a flatter face w/a smaller jaw + reduced prognathism
this is to allow skull to balance on top of spine + achieve balance
evolution of the pelvis
apes had a long + narrow pelvis
humans have a short, broad + bowl shaped pelvis
this is to support abdominal organs + foetus during pregnancy
also provides stability for bipedal locomotion
broad hip bone also allows attachment of buttock muscles to move the legs + keep upper body erect
the femur/carrying angle in apes
femur attached directly to pelvis
has a very little carrying angle
weight tends to not fall outside of femur
less stability when standing bipedally
the femur/carrying angle in humans
head of femur fits into acetabulum of the pelvis
femur tends to converge towards the knees
this creates a carrying angle, which allows weight distribution to stay close to the central axis of the body
allows weight of body to be transferred from pelvis to legs
allows greater stability in upright posture + when walking enables body to be rotated at lower leg + foot and each step has a straight line
acetabulum
hip socket of the pelvis
the knee in apes
body weight transmitted to inside of the knee
this is less strong, so the medial condyle (inside) serves as a stronger point
the knee in humans
body weight transmitted down the outside of the knee
this makes the lateral condyle (outside) become stronger
this produces a joint that requires no energy to support body in a standing position + body weight
the foot in apes
abducted/splayed big toe
flat foot w/only longitudinal arch
relatively smaller calcaneous (heel) + talus (ankle) bones
this does not support bipedalism
the foot in humans
adducted, robust big toe
the metatarsals are arranged in a way to form a longitudinal + transverse arch
this enables bipedalism
apes centre of gravity
arms longer than legs
higher centre of gravity at the chest
this allows for quadrupedalism
humans centre of gravity
legs longer than arms
this increases the length of the stride when walking
this lowers the centre of gravity to the pelvis
this allows stability when moving bipedally or standing erect
humans muscle tone
the muscles that move the spine, hip, knee + ankle are partially
muscle tone
the partial contraction of skeletal muscles
apes striding gait
apes lack wide pelvis + carrying angle
this means they sway from side to side when walking bipedally so that the weight is over each leg in turn
humans striding gait
when the foot hits the ground, weight transmitted from the heel along the outside of the foot via the transverse arch
at final moment of walk, whole weight of body is propelled by big toe via longitudinal arch
forward arm swinging keeps shoulders at right angles + red energy expelled
foot steps follow a straight line
striding gait
walking upright in a way that the hip + knee are fully extended
advantages to bipedalism
is a more energy-efficient means of moving.
leaves the hands free to use tools.
leaves the hands free to carry items.
The upright stance achieves greater height, thus the ability to see further.
The upright stance means that less of the body is exposed to sunlight.
The upright stance inc exposure to breezes, inc cooling mechanisms.
relative size of cerebal cortex evolution
brain size has inc due to inc size of cerebrum
would have inc due to nat selection of using visual + tactile perception in arboreal env’t to locate food
brains of hominids are highly convoluted which inc S.A, and therefore cerebral cortex
inc in size of cerebral cortex also allows greater variety of behaviours to meet env’t problems e.g interactions w/allies + grooming
mobility of digits evolution
pentadactyl limbs
digits are highly mobile
prehensile digits were essential for climbing in arboreal env’t
however, has evolved into inc ability to move digits independently of one another
thumb is opposable but not our big toe as we are weight bearing
having opposable thumbs allow precision (e.g holding pencil) + power grip
however, apes only have power grip as they have short thumbs
how have digits evolved
claws of primates have flattened to become nails
this assts w/grasping action
development of fingerprints also occurred which inc sensitivity + gripping ability
locomotion evolution
change from quadrupedalism to bipedalism
prognathism + dentition in apes
primitive mammals had 44 teeth + dental formula of 3:1:4:3, meaning 3 incisors, 1 canine, 4 premolars + 3 molars on each side of jaw
some old monkeys used to have large canines + a diastema
teeth were in a U shape
prognathism + dentition in humans
have 32 teeth + dental formula of 2:1:2:3, meaning 2 incisors, 1 canine, 2 pre molars + 3 molars on either side of jaw
no diastema
has evolved into a parabolic shape
prognathism + brow ridges in apes
had a forward cutting, prognathic jaw + a distinct brow ridge
brow ridge located above the eye sockets
tooth size was a lot larger
prognathism + brow ridges in humans
prognathic jaw has dec over time
teeth have become smaller, leading to a flatter face + development of a chin + prominent nose
inc size of the frontal lobe means the cranium is extended forward, dec brow ridges
brachiation
form of arboreal locomotion where by the arms are used to swing from one hold to another
brachiation - shoulders
Shorter clavicle = greater mobility + rotation of the shoulder joint
Movement of scapulae (shoulder blades) from side of chest to the back + higher up = larger range of shoulder motion
Shoulder socket faces towards the back = allows the humerus to rotate freely in multiple directions = enhances the ability to reach out in various angles + absorb the forces of swinging
brachiation - arms
Longer arms = inc reach, allowing brachiators to span greater distances between branches
Flexible elbow joint = allows for smooth extension + flexion during the swing cycle, helping to adjust grip + momentum mid-swing
brachiation - hands
Robust, flexible wrist joint = absorbs the impact forces during branch contact, allows for quick adjustments in hand position, aiding in stability + control
Long, curved fingers = grasping branches
Short thumb = red interference during swinging, makes it easier to hook fingers around branches
how long ago did australopithecines live on earth
3.56 million years
who discovered the australopithecines fossil + when
Raymond Dart in south Africa in the 1920’s
features of the australopithecines fossil that indicate bipedal
deep impression showing heel hit ground first + where toe used to push off
big toe parallel to other digits
well developed longitudinal arch
features that indicate ‘Lucy’ is australopithecus afarensis
dental arcades
size of canines
prominence of cusps on cheek teeth
features of australopithecines
teeth like a hominin
canines short + projecting
incisors + canines make a row of cutting teeth w/no gap
parabolic shape
low forehead
jaw more upper + lower projecting than modern humans
brain size 480cm³
body weight 1/3 gorilla
brain size between chimpanzees + humans
bipedal gait
femur, pelvis + carrying angle similar to humans
pelvic + foot bone has a non opposable big toe
foramen magnum more forward than other apes
S shaped spine
thumb short + less mobile for arboreal lifestyle
features of australopithecus afarensis
3.9 and 2.8 million years ago
East Africa
Female: 105–110 cm
Males: 150 cm
brain size 430 cm3
Low, sloping forehead
Prominent brow ridges
Short sagittal crest in males
Prognathic jaw
Small canine teeth (but larger than
A. africanus)
Diastema present
Big toe not opposable
Long arms, shorter than the legs
Long curved fingers + toes
Short and wide pelvis
features of australopithecus africanus
3.2 to 2 million years ago
Southern Africa
Female: 110 cm
Males: 135 cm
brain = 480 cm3
Slightly arched forehead
Smaller brow ridge
Prognathic jaw
Shorter + smaller incisors + canines
Large molar + premolars
No diastema
Big toe not opposable
Long arms, shorter than the legs
Some curvature of finger + toe bones
Short + wide pelvis, less rounded than in modern humans
skull characteristics in apes
Thicker bones forming cranium
Face large compared to cranial size
Smaller cranial capacity
Heavier brow ridges
No forehead or sloping forehead
Lower cranium
Less prominent cheek bones
Possible saggital crest on top of skull
Foramen magnum towards back of skull
skull characteristics in humans
Thinner bones forming cranium
Face small compared to cranial size
Larger cranial capacity
Brow ridges red or absent
Inc larger + more vertical forehead
More dome-shaped cranium
More prominent cheek bones
No crest on top of skull
Foramen magnum under centre of skull
mandible + teeth characteristics in apes
More prognathic jaw
Larger jaw
Heavier, thicker mandible
No chin
Larger teeth, especially molars
Diastema present
Canine teeth more prominent
Difference between size of incisors and
molars
mandible + teeth characteristics in humans
Flatter face
Smaller jaw
More slender, thinner mandible
Inc definite chin
Smaller teeth
No diastema
Canine teeth less prominent
More even teeth/little diff in size of incisors + molars
torso characteristics in apes
narrower pelvis
back vertebrae less wedge shaped
wide, barrel shaped rib cage
torso characteristics in humans
broader pelvis
lumbar vertebrae more wedge shaped
smaller ribcage
upper limbs characteristics in apes
shorter thumb that is less mobile
fingers longer + more curved
upper limbs characteristics in humans
longer thumb with inc opposability
fingers straighter + shorter
lower limbs characteristics in apes
femurs more parallel
arms longer than legs
lower limbs characteristics in humans
femurs sloping inwards towards the knee
arms shorter than legs
when was the paranthropus robustus fossil found
in 1938 by robert broom
features of paranthropus robustus
females' height of approximately 1 m + males’ height of
approximately 1.2 m
existed 1.8 to 1.2 million years ago
found in south africa
cranial capacity of 520 cm3
large sagittal crest for attachment of strong chewing muscles
very large molars and premolars, with small incisors and
canines by comparison
prognathism, although less than australopithecines
wide, dish-shaped face with large zygomatic arches
heavy brow ridges
structures for bipedalism.
when was homo habillis found
in 1964 by Dr Louis Leakey
features of homo habillis
existed 2.3 to 1.5 million years ago
found in south africa
females’ height of 110 cm + males’ height of 130 cm
brain size of 610 cm3
rounder skull
small brow ridge
central foramen magnum
moderate prognathism
teeth arranged in a rounder arc
relatively short legs and long arms
slightly curved finger bones, indicating a
strong power grip
able to form a precision grip
when was homo erectus found
in 1927 by Dr Davidson Black. first fossil found to show modern human like bodies
features of homo erectus
existed 1.9 mill years ago to 110000 years ago
in africa, asia + maybe europe
varied height, ranging from 145 cm to 185 cm
short, stocky body with thicker bones, suggesting a demanding lifestyle
average cranial capacity of 1050 cm3
low, sloping forehead
defined brow ridges
large, thick jaw without a chin
red size of molars
when was homo neanderthalensis found
in 1856 in neander valley