Unit 2: Exam Revision Flashcards
What is the purpose of The Cell Cycle?
To allow somatic cells to divide
What occurs in Step 1 of CC?
Interphase (DNA replication and cell growth)
What occurs in Step 2 of CC?
Mitosis
What occurs in Step 3 of CC?
Cytokinesis (Division of cytoplasm)
What occurs in each sub-stage of the Interphase?
G1- Cell Growth
S- DNA Replication
G2- Cell Growth
What are the 4 phases of Mitosis in order?
P-Prophase
M-Metaphase
A-Anaphase
T-Telophase
What is the purpose of Mitosis?
To produce identical daughter cells as original/parent
How many daughter cells are produced in Mitosis?
2
What is a somatic cell?
Any cell other then germline cell (sperm or egg)
What is Asexual Reproduction?
Reproduction without sex
Name 3 ADVANTAGES of Asexual Reproduction
Rapid Population Growth
Single Parent Organism
Uses little energy
Name 3 DISADVANTAGES of Asexual Reproduction
Little Genetic Variation
Rapid Population Growth (may lead to competition for resources)
Any mutation in parent will be passed on
Name 5 ways of Asexual Reproduction
Binary Fission (splits into 2 equal parts, then grows) Splitting (splits into many parts, organisms grow from part) Spore Formation (organism breaks into multiple pieces to be carried away and grow) Budding (new organisms form off of parent) Vegetative Propagation (creating new plants from stems/leaves/roots of parent organism)
What is the purpose of Meiosis?
Cell division which creates gametes, all being genetically different
What are the Gametes and Gonads in males and femals
Female Gamete = Eggs, Female Gonad = Ovaries
Male Gamete = Sperm, Male Gonad = Testes
What is the Diploid number?
Total number of chromosomes in a somatic cell. 2n
What is the Haploid number?
Total number of chromosomes in a germline cell/gamete n
What is the process of sperm production called?
Spermatogenisis
How long does it take to produce 1 sperm cell?
64-72 days
produced from puberty until death
What is the process of egg production called?
Oogenesis
Eggs released from puberty until menapause
What does Antenatal mean?
Human pre-birth development
What does Gestational Age mean?
Length of pregnancy from last menstruation
Where does fertilisation of an egg occur?
Fallopian Tube
What is Nondisjunction?
Occurs when Chromosomes fail to separate properly
Name 2 ADVANTAGES of Sexual Reproduction
- Genetic Diversity
- Equips population with ability to survive change
Name 2 DISADVANTAGES of Sexual Reproduction
- Energy Requirements (must find and secure a mate)
- Elaborate Courtship
What does Gastrulation mean?
Organisation of inner cell mass into three primary germ layers.
What are the 3 primary germ layers?
- Ectoderm
- Mesoderm
- Endoderm
What are the Primary Germ layers made of?
Stem Cells
What are the 3 types of Stem Cells?
Totipotent, Pluripotent and Multipotent
What is a teratogen?
A factor which can cause a malformation in an embryo.
At which stage of the Interphase does DNA synthesis occur?
S stage of Interphase
What does undifferentiated mean?
Stem Cell has not yet turned into a specific cell
Embryonic Stem Cells are considered to be…
Totipotent
What cells can be produced from each primary germ layer?
Ectoderm- Skin Cell
Mesoderm- Blood Cell
Endoderm- Lung Cell
What are the 3 main stages that occur during human prenatal development?
Zygote, Embryo & Foetus
What are the 2 main components of the blastocyst?
Fluid and Outer Layer
What is a blastocyst?
A fluid filled structure with an inner cell mass surrounded by an outer layer of cells
How long is the embryonic period?
Approx 9 weeks following fertilisation
How long is the fetal period?
From 9 weeks until birth
How do Stem Cells divide?
Mitosis
What is a difference between a cancerous cell and a normal cell?
Cancerous cells do not respond to signals telling them to stop dividing
What is a source of Embryonic Stem Cells?
From inner cell mass in blastocyst
What is a mutagen?
An environmental factor that causes genetic mutations
What is recombination (crossing over)
Process of generating new combinations of alleles (genetic variation)
Where does recombination occur in Meiosis?
Prophase I
What occurs in Cytokinesis?
Cytoplasm is equally divided between daughter cells
What does genome mean?
The complete set of genetic material present within a haploid set of chromosomes
What is a gene?
Specific segment of DNA on a chromosome, which code for different traits.
What is an allele?
A different version of the same gene
What are the 4 Nucleotide bases?
Adenine, Thymine, Guanine and Cytosine
How do the bases pair?
A pairs with T
C pairs with G
Which scientist developed the concept of genes?
Gregor Mendel
What is meant by the term dominant?
A trait which is expressed in a heterozygous pair
What is meant by the term recessive?
A trait which is NOT expressed in a heterozygous pair
What is a Karyotype?
Visual representation of chromosomes, sorted into homologous pairs from largest to smallest.
What genetic difference does a person with Down Syndrome have?
3 chromosomes in the 21st group instead of 2
What genetic difference does a person with Kinefelter Syndrome have?
3 sex chromosomes instead of 2
What are the 3 types of Chromosomal changes?
Duplication, Deletion and Translocation
What does phenotype mean?
Visual expression of an organisms genetic makeup
What does genotype mean?
Genetic makeup which determines the phenotype
What does autosome mean?
Any chromosome which isn’t a sex chromosome
What does homozygous mean?
Having 2 identical alleles
What does heterozygous mean?
Having 2 different alleles
What does locus mean?
Location of a gene on a chromosome
What is a polygene?
Group of genes which express a phenotype only when all shown
What is an example of a Polygenic Trait?
Height, Eye Colour, Skin Colour etc
What does autosome mean?
22 pairs of chromosomes (not sex chromosomes)
What does non-homologous pair mean?
Refers to a non-matching pair
What is the Kinetochore?
Attachment point for spindle fibre (surrounds centromere)
What is the Telomere?
Ends of chromosome, prevent chromosomes from sticking together
What is co-dominance?
Heterozygous organism showing both alleles in phenotype
What is dominant?
Refers to trait which IS expressed in heterozygous pair.
What is recessive?
Refers to trait which IS NOT expressed in a heterozygous pair
Name 2 benefits of The Human Genome Project:
Helps to understand Human Evolution
Can be used to develop treatments or diagnoses for genetic disorders
What genetic difference does a person with Turner’s Syndrome have?
1 sex chromosome instead of 2 (XO)
What is DNA?
Chain of nucleotides which contain the genetic instructions used to encode life
What is Chargaff’s Rule?
Corresponding bases have equal proportions
eg. A and
What is the difference between Ideogram and Karyotype?
Ideogram shows individual chromosomes, karyotypes shows homologous pairs
What is the difference between an Autosome and a Sex Chromosome?
Autosomes control body characteristics and somatic cells, sex chromosomes determine the sex of individual
What is the difference between Haploid and Diploid?
Haploid is number of chromosomes in gamete, diploid is number of chromosomes in somatic cell
What is the difference between Centromere and Kinetochore?
Centromere is where sister chromatids join, Kinetochore is protein structure which forms spindle fibres
What is the difference between Monosomy and Trisomy?
Monosomy is when 1 chromosome is present, Trisomy is when 3 chromosomes are present
What is a homologous chromosome pair made of?
1 Paternal chromosome and 1 Maternal chromosome
What is Epigenetics?
The alteration of the physical structure of DNA, which affect how genes are read
What is continuous variation?
Variation which has no limit on the number of possibilities which can occur. Eg Height
What is discontinuous variation?
When individuals can be grouped into categories based on limited outcomes. Eg Blood Type