Genetics and Evolution Flashcards
what is in the male reproductive system
- penis
- vas deferens
- urethra
- scrotum
- testicles
- epididymis
- prostate gland
- seminal vesicle
what is in the female reproductive system
- uterus
- fallopian tube
- ovaries
- vagina
- cervix
what are the fetus’s development stages
- zygote
- embryo
- fetus
- baby
what is a gamete
a female or male sex cell (sperm or egg) that can fertilise during sex to form a zygote.
what is fertilisation
the fusing of gametes ( sperm + egg)
what is a Zygote
a single cell formed by the fusion of 2 gametes
what is DNA
(deoxyribonucleic acid) made up of 4 base pairs:
A= adedine
T= Thymine
G= Guanine
C= cytosine
what does DNA do
carries genetic information
what is a gene
a gene is a section of DNA what codes for a specific characterisation
what is a chromosome
a length of DNA which is made up of many genes.
how many chromosomes do humans have
46 body cells
23 sex cells
what is a haploid cell
Haploid
- one set of chromosomes
- in humans = 23
- in humans gametes are haploid
what is a Diploid cell
Diploid
- two sets of chromosomes
- in humans = 46
- in humans, all body cells except gametes are diploid
what would happen if DNA was altered during cell division
this can lead to growth defects or could be fatal
why is it important that DNA makes exact copies of itself
this is important as original cell holds all DNA needed to make particular proteins, coding for different types of cells in body.
what is mutation
an accidental alteration in a genetic message, a mutation may be harmful or helpful, big or small.
what is a chromosomal mutation
an error that effects an entire chromosome this can cause chromosomal disorders like down syndrom
what is gene mutation
an error in a length of DNA which effects he expression of a gene.
what are the causes of mutation
- radiation: UV light or gamma rays
- Accidental DNA damage during cell division
- Chemicals: such as those found in smoke
what is a punnet square
determines genotypes and phenotypes in two characters
what is variation
the differences between indivuals.
what causes variation
combination of genes we inherit and environment we live in
environmental factors that affect our phenotype are:
- diet
- culture
- geography
- pollution
- climate
what is discrete variation
you are either one thing or another. controlled by one pair of genes
what is continuous variation
characterisations that change gradually over a range of time. controlled by more than one pair of genes
what is Meiosis
cell division responsible for producing sperm or egg cells
- reproduction
- 2 divisions
- 4 daughter cells
- genetically varied
- alleles swapped
- sex cells (swapped)
what is Mitosis
cell division responsible for growth and repair
- 1 division
- 2 daughter cells
- genetically identical cells
- somatic (body) cells
what is selective breeding
choosing parents with particular characteristics to breed together and produce offspring with more desirable characteristics.
disadvantages of selective breeding
- offspring share genes= more chance of diseases
- reduced gene pool= more vulnerable
- loss of genetic variety
- less chance of adoption to changed environment
what is Fitness
a organism’s capacity to survive and reproduce in a changing environment
what is natural selection
a species’ ability to adapt to a changing environment
what is evolution
evolution is the change in characteristics of a species over several generations
what is scientific theory
and explanation based on extensive and repeated experimentation.
