Genetics Flashcards
What is heterozygous? (Genetics)
- two things different or distinct (different alleles)
What is homozygous? (Genetics)
- two things are the same (same alleles)
- upper case = dominant
- lower case = recessive
What would the name for “bb” ? (Genetics)
- homozygous recessive
What would be the name for “BB” ? (Genetics)
- homozygous dominant
What would be the name for “Bb” ? (Genetics)
- heterozygous (doesn’t need dominant / recessive)
What chromosomes do males carry? (Genetics)
X Y
What chromosomes do females carry? (Genetics)
X X
What is a gene? (Genetics)
- specific region of DNA that codes for a protein, which will usually present a trait. (ie: hair colour gene).
What is a genome? (Genetics)
- entire DNA sequence for a species.
What are alleles? (Genetics)
- different forms of a gene. Humans have 2 per trait (1 from mom and 1 from dad). Usually located in the same position on a chromosome (ie: brown hair allele vs. blonde hair allele).
What is dominant? (Genetics)
- allele / trait that is fully showing. Denoted by capital letter.
What is recessive? (Genetics)
- allele / trait that is hidden it masked when paired with a dominant trait. Denoted by the same letter but lower - case.
What is a genotype? (Genetics)
- combination of alleles an organism has for a given trait (ie: BB, Bb, bb).
What is a phenotype? (Genetics)
- the observable trait based on the alleles.
What does “P” mean in genetics?
- parent generation
What does “F1” mean in genetics?
- first generation (children)
What does “F2” mean in genetics?
- second generation (grandchildren)
Monohybrid crosses: what are the 2 laws of heredity? (Explain) (Genetics)
1) law of segregation: inherited traits are determined by pairs of alleles - one from the sperm and one from the egg.
2) law of dominance: one allele for a trait is dominant and one is recessive. The dominant trait one, if present, can hide the recessive one.
Monohybrid crosses: what is a punnet square? (Genetics)
- used to show all the possible allele combinations.
Monohybrid crosses: what is a mutant type? (Genetics)
- abnormal type.
What are dihybrid crosses?
- dihybrid crosses are used to determine the probability of genotypes and phenotypes involving TWO (2) different genes simultaneously.
Sex Linkage: what are sex chromosomes? (Genetics)
- X and Y are not exactly homologous to each other.
- the Y chromosome is much smaller than the X chromosome.
- the Y chromosome contains about 200 genes whereas the X chromosome contains over 1400 genes!
What are 3 characteristics of homologous chromosomes? (Genetics)
- shape
- size
- gene arrangement
What is Co - Dominance & Incomplete Dominance? (Basic explanation) (Genetics)
Incomplete Dominance: blend of the two phenotypes (CrCr)
Co - Dominance: alleles are fully at the same time (BB)
What are 3 characteristics of karyotyping features? (Genetics)
- chromosomes pairs with the same size and bonding patterns
- sex chromosomes are always placed last
- 1st 22 pairs are called AUTOSOMES
What determines the sex of the baby? (Genetics)
- the father
What are spontaneous mutations?
- random errors in DNA replication (mitosis and meiosis)
What are induced mutations? (Genetics)
- arise from a factor called MUTAGEN
What are 2 factors of chromosomal mutations? (Genetics)
- can occur in BOTH mitosis and meiosis
- right number of chromosomes, but the chromosome is “messed up”
What are examples of common mutagens? (Genetics)
- X-rays
- UV radiation
- viruses
- chemicals
What is non disjunction? (Genetics)
- another form of mutation caused by incorrect meiosis (missing chromosome = 22 | extra chromosome = 24)
How many chromosomes should every human have in total? (Genetics)
- 46 (23 from each parent)
What are the 2 types of aneuploidy? (Explain) (Genetics)
- monosomy: zygote is missing 1 chromosome
- trisomy: zygote has 1 extra chromosome
What is mitosis? (Genetics)
• type of nuclear division (duplicates body cells ONLY)
• at the end, the cell divides to form 2 IDENTICAL cells called daughter cells.
• occurs in somatic cells (non - sex cells)
How many stages of mitosis? (Genetics)
4
What are the stages of mitosis? (Just name!) (Genetics)
PMAT:
- prophase
- metaphase
- anaphase
- telophase / cytokinesis
What is the diffence between chromatin and chromosomes? (Mitosis: Genetics)
- A chromosome consists of a single, double-stranded DNA molecule while
a chromatin consists of two DNA strands joined together by their centromere.
What is prophase? (Mitosis: Genetics)
• chromosomes become visible
• nuclear membrane breaks down
• paires of centrioles move to opposite ends of the cell
• spindle fibres form from the centrioles
What is metaphase? (Mitosis: Genetics)
• chromosomes line up in the middle of the cell to form the metaphase plate
• each chromosome attaches to a spindle fibre at its centromere
What is anaphase? (Mitosis: Genetics)
• spindle fibres pull on and split the centromeres
• sister chromatids move to opposite sides of the cell
What is telophase? (Mitosis: Genetics)
• chromosomes reach opposite sides of the cell
• new nuclear membranes form around the chromosomes
• chromosomes relax to form chromatin
• spindle fibres disappear
• cytokinesis begins
What is the cytokinesis for animal cells? (Mitosis: Genetics)
- cleavage furrow
What is the cytokinesis for plant cells? (Mitosis: Genetics)
- cell plate
What are somatic cells? (Mitosis: Genetics)
- non sex cells
What are the stages of meiosis? (Just name!) (Genetics)
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1 and cytokinesis
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2 and cytokinesis
What is meiosis? (Genetics)
• cell division that creates 4 gametes (sperm or egg cells) that are genetically different
• each gamete contains 1/2 the total #
of chromosomes = 23 chromosomes
in total
• occurs in testes and ovarles
What are the 2 stages of meiosis? (Genetics)
• meiosis 1: homologous chromosomes
are separated
• meiosis 2: sister chromatids are
separated
(At the end of meiosis, 4 haploid cells with genetic diversity are created).
What happens in the end of meiosis? (Genetics)
• spermatogenesis: 4 equally - sized sperm cells are produced.
• oogensis: 1 large egg cell and 3 polar bodies are produced.
• fertilization: sperm (23 chromosomes)
+ egg (23 chromosomes) = zygote (46
chromosomes).
What is prophase 1? (Meiosis: Genetics)
• nuclear membrane dissolves, centrioles migrate to opposite ends, and spindle fibres form
• homologous chromosomes pair up in a process called synapsis to form a
“tetrad” structure
• homologous exchange a section of
DNA in a process called crossing - over as this creates genetic variation*
What is metaphase 1? (Meiosis: Genetics)
• spindle fibres attach onto homologous
• homologous chromosomes line up randomly in the middle to form the metaphase plate as this creates genetic variation *
• thus is called independent assortment
What is anaphase 1? (Meiosis: Genetics)
• spindle fibres pull apart the homologous chromosomes
• chromosomes move to opposite ends of the cell
What is telophase 1 / cytokinesis? (Meiosis: Genetics)
• nuclear membrane begins to reform
• spindle fibres disappear
• cytokinesis cause cell division
• END RESULT: 2 haploid daughter cells that are genetically different from the parent cell are produced
What is prophase 2? (Meiosis: Genetics)
• nuclear membrane dissolves and spindle fibres form
What is metaphase 2? (Meiosis: Genetics)
• spindle fibres attach onto chromosomes
• chromosomes line up in the middle to form the metaphase plate
What is anaphase 2? (Meiosis: Genetics)
• spindle fibres pull apart the chromosomes
• sister chromatids move to opposite ends of the cell
• *similar to mitosis but half # of chromosomes
What is telophase 2? (Meiosis: Genetics)
• nuclear membrane begins to reform
• spindle fibres disappear
• cytokinesis causes cell division
• END RESULT: in total, 4 haploid daughter cells (containing 23 chromosomes) that are genetically different from the parent cell are produced
What is diploid? (Meiosis: Genetics)
• cell that has 2 sets of chromosomes (46 in total)
What is haploid? (Meiosis: Genetics)
• cell that has 1 set of chromosomes (23 in total)
